diff --git a/Apollo.xcodeproj/project.pbxproj b/Apollo.xcodeproj/project.pbxproj
index 5241743ae7..c15264c95d 100644
--- a/Apollo.xcodeproj/project.pbxproj
+++ b/Apollo.xcodeproj/project.pbxproj
@@ -21,6 +21,9 @@
 		9BDE43D122C6655300FD7C7F /* Cancellable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BDE43D022C6655200FD7C7F /* Cancellable.swift */; };
 		9BDE43DD22C6705300FD7C7F /* GraphQLHTTPResponseError.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BDE43DC22C6705300FD7C7F /* GraphQLHTTPResponseError.swift */; };
 		9BDE43DF22C6708600FD7C7F /* GraphQLHTTPRequestError.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BDE43DE22C6708600FD7C7F /* GraphQLHTTPRequestError.swift */; };
+		9BE071AD2368D08700FA5952 /* Collection+Helpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BE071AC2368D08700FA5952 /* Collection+Helpers.swift */; };
+		9BE071AF2368D34D00FA5952 /* Matchable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BE071AE2368D34D00FA5952 /* Matchable.swift */; };
+		9BE071B12368D3F500FA5952 /* Dictionary+Helpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BE071B02368D3F500FA5952 /* Dictionary+Helpers.swift */; };
 		9BEDC79E22E5D2CF00549BF6 /* RequestCreator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BEDC79D22E5D2CF00549BF6 /* RequestCreator.swift */; };
 		9BF1A94F22CA5784005292C2 /* HTTPTransportTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BF1A94C22CA54F9005292C2 /* HTTPTransportTests.swift */; };
 		9BF1A95122CA6E71005292C2 /* GraphQLGETTransformer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9BF1A95022CA6E71005292C2 /* GraphQLGETTransformer.swift */; };
@@ -36,7 +39,7 @@
 		9F438D081E6C30B1007BDC1A /* StarWarsAPI.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 9FCE2CFA1E6C213D00E34457 /* StarWarsAPI.framework */; };
 		9F533AB31E6C4A4200CBE097 /* BatchedLoadTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9F438D0B1E6C494C007BDC1A /* BatchedLoadTests.swift */; };
 		9F55347B1DE1DB2100E54264 /* ApolloStore.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9F55347A1DE1DB2100E54264 /* ApolloStore.swift */; };
-		9F578D901D8D2CB300C0EA36 /* Utilities.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9F578D8F1D8D2CB300C0EA36 /* Utilities.swift */; };
+		9F578D901D8D2CB300C0EA36 /* HTTPURLResponse+Helpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9F578D8F1D8D2CB300C0EA36 /* HTTPURLResponse+Helpers.swift */; };
 		9F65B1211EC106F30090B25F /* Apollo.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 9FC750441D2A532C00458D91 /* Apollo.framework */; };
 		9F69FFA91D42855900E000B1 /* NetworkTransport.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9F69FFA81D42855900E000B1 /* NetworkTransport.swift */; };
 		9F7BA89922927A3700999B3B /* ResponsePath.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9F7BA89822927A3700999B3B /* ResponsePath.swift */; };
@@ -101,7 +104,7 @@
 		9FE1C6E71E634C8D00C02284 /* PromiseTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FE1C6E61E634C8D00C02284 /* PromiseTests.swift */; };
 		9FE941D01E62C771007CDD89 /* Promise.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FE941CF1E62C771007CDD89 /* Promise.swift */; };
 		9FEB050D1DB5732300DA3B44 /* JSONSerializationFormat.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FEB050C1DB5732300DA3B44 /* JSONSerializationFormat.swift */; };
-		9FEC15B41E681DAD00D461B4 /* Collections.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FEC15B31E681DAD00D461B4 /* Collections.swift */; };
+		9FEC15B41E681DAD00D461B4 /* GroupedSequence.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FEC15B31E681DAD00D461B4 /* GroupedSequence.swift */; };
 		9FF33D811E48B98200F608A4 /* HTTPNetworkTransport.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9F4DAF2D1E48B84B00EBFF0B /* HTTPNetworkTransport.swift */; };
 		9FF90A611DDDEB100034C3B6 /* GraphQLResponse.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FF90A5B1DDDEB100034C3B6 /* GraphQLResponse.swift */; };
 		9FF90A651DDDEB100034C3B6 /* GraphQLExecutor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FF90A5C1DDDEB100034C3B6 /* GraphQLExecutor.swift */; };
@@ -283,6 +286,9 @@
 		9BDE43D022C6655200FD7C7F /* Cancellable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Cancellable.swift; sourceTree = "<group>"; };
 		9BDE43DC22C6705300FD7C7F /* GraphQLHTTPResponseError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GraphQLHTTPResponseError.swift; sourceTree = "<group>"; };
 		9BDE43DE22C6708600FD7C7F /* GraphQLHTTPRequestError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GraphQLHTTPRequestError.swift; sourceTree = "<group>"; };
+		9BE071AC2368D08700FA5952 /* Collection+Helpers.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Collection+Helpers.swift"; sourceTree = "<group>"; };
+		9BE071AE2368D34D00FA5952 /* Matchable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Matchable.swift; sourceTree = "<group>"; };
+		9BE071B02368D3F500FA5952 /* Dictionary+Helpers.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Dictionary+Helpers.swift"; sourceTree = "<group>"; };
 		9BEDC79D22E5D2CF00549BF6 /* RequestCreator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RequestCreator.swift; sourceTree = "<group>"; };
 		9BF1A94C22CA54F9005292C2 /* HTTPTransportTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = HTTPTransportTests.swift; sourceTree = "<group>"; };
 		9BF1A95022CA6E71005292C2 /* GraphQLGETTransformer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GraphQLGETTransformer.swift; sourceTree = "<group>"; };
@@ -296,7 +302,7 @@
 		9F438D0B1E6C494C007BDC1A /* BatchedLoadTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = BatchedLoadTests.swift; sourceTree = "<group>"; };
 		9F4DAF2D1E48B84B00EBFF0B /* HTTPNetworkTransport.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = HTTPNetworkTransport.swift; sourceTree = "<group>"; };
 		9F55347A1DE1DB2100E54264 /* ApolloStore.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ApolloStore.swift; sourceTree = "<group>"; };
-		9F578D8F1D8D2CB300C0EA36 /* Utilities.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Utilities.swift; sourceTree = "<group>"; };
+		9F578D8F1D8D2CB300C0EA36 /* HTTPURLResponse+Helpers.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "HTTPURLResponse+Helpers.swift"; sourceTree = "<group>"; };
 		9F69FFA81D42855900E000B1 /* NetworkTransport.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = NetworkTransport.swift; sourceTree = "<group>"; };
 		9F7BA89822927A3700999B3B /* ResponsePath.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ResponsePath.swift; sourceTree = "<group>"; };
 		9F8622F71EC2004200C38162 /* ReadWriteFromStoreTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ReadWriteFromStoreTests.swift; sourceTree = "<group>"; };
@@ -379,7 +385,7 @@
 		9FE1C6E61E634C8D00C02284 /* PromiseTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PromiseTests.swift; sourceTree = "<group>"; };
 		9FE941CF1E62C771007CDD89 /* Promise.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Promise.swift; sourceTree = "<group>"; };
 		9FEB050C1DB5732300DA3B44 /* JSONSerializationFormat.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = JSONSerializationFormat.swift; sourceTree = "<group>"; };
-		9FEC15B31E681DAD00D461B4 /* Collections.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Collections.swift; sourceTree = "<group>"; };
+		9FEC15B31E681DAD00D461B4 /* GroupedSequence.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GroupedSequence.swift; sourceTree = "<group>"; };
 		9FF90A5B1DDDEB100034C3B6 /* GraphQLResponse.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GraphQLResponse.swift; sourceTree = "<group>"; };
 		9FF90A5C1DDDEB100034C3B6 /* GraphQLExecutor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GraphQLExecutor.swift; sourceTree = "<group>"; };
 		9FF90A6A1DDDEB420034C3B6 /* InputValueEncodingTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = InputValueEncodingTests.swift; sourceTree = "<group>"; };
@@ -530,6 +536,7 @@
 			isa = PBXGroup;
 			children = (
 				9BDE43D022C6655200FD7C7F /* Cancellable.swift */,
+				9BE071AE2368D34D00FA5952 /* Matchable.swift */,
 			);
 			name = Protocols;
 			sourceTree = "<group>";
@@ -727,14 +734,16 @@
 			children = (
 				9FCDFD221E33A0D8007519DC /* AsynchronousOperation.swift */,
 				9B1CCDD82360F02C007C9032 /* Bundle+Helpers.swift */,
+				9BE071AC2368D08700FA5952 /* Collection+Helpers.swift */,
+				9BE071B02368D3F500FA5952 /* Dictionary+Helpers.swift */,
 				9BA3130D2302BEA5007B7FC5 /* DispatchQueue+Optional.swift */,
+				9FEC15B31E681DAD00D461B4 /* GroupedSequence.swift */,
+				9F578D8F1D8D2CB300C0EA36 /* HTTPURLResponse+Helpers.swift */,
+				9FADC8491E6B0B2300C677E6 /* Locking.swift */,
 				9FE941CF1E62C771007CDD89 /* Promise.swift */,
 				9BA1245D22DE116B00BF1D24 /* Result+Helpers.swift */,
 				9F19D8431EED568200C57247 /* ResultOrPromise.swift */,
-				9FEC15B31E681DAD00D461B4 /* Collections.swift */,
-				9FADC8491E6B0B2300C677E6 /* Locking.swift */,
 				9B1A38522332AF6F00325FB4 /* String+SHA.swift */,
-				9F578D8F1D8D2CB300C0EA36 /* Utilities.swift */,
 			);
 			name = Utilities;
 			sourceTree = "<group>";
@@ -1216,7 +1225,9 @@
 				9F86B68B1E6438D700B885FF /* GraphQLSelectionSetMapper.swift in Sources */,
 				9F55347B1DE1DB2100E54264 /* ApolloStore.swift in Sources */,
 				9BDE43D122C6655300FD7C7F /* Cancellable.swift in Sources */,
+				9BE071B12368D3F500FA5952 /* Dictionary+Helpers.swift in Sources */,
 				9F69FFA91D42855900E000B1 /* NetworkTransport.swift in Sources */,
+				9BE071AF2368D34D00FA5952 /* Matchable.swift in Sources */,
 				9FCDFD291E33D0CE007519DC /* GraphQLQueryWatcher.swift in Sources */,
 				9FC2333D1E66BBF7001E4541 /* GraphQLDependencyTracker.swift in Sources */,
 				9F19D8441EED568200C57247 /* ResultOrPromise.swift in Sources */,
@@ -1232,8 +1243,8 @@
 				C377CCA922D798BD00572E03 /* GraphQLFile.swift in Sources */,
 				9FC9A9CC1E2FD0760023C4D5 /* Record.swift in Sources */,
 				9FC4B9201D2A6F8D0046A641 /* JSON.swift in Sources */,
-				9FEC15B41E681DAD00D461B4 /* Collections.swift in Sources */,
-				9F578D901D8D2CB300C0EA36 /* Utilities.swift in Sources */,
+				9FEC15B41E681DAD00D461B4 /* GroupedSequence.swift in Sources */,
+				9F578D901D8D2CB300C0EA36 /* HTTPURLResponse+Helpers.swift in Sources */,
 				9F7BA89922927A3700999B3B /* ResponsePath.swift in Sources */,
 				9FC9A9BD1E2C271C0023C4D5 /* RecordSet.swift in Sources */,
 				9BF1A95122CA6E71005292C2 /* GraphQLGETTransformer.swift in Sources */,
@@ -1242,6 +1253,7 @@
 				9F27D4641D40379500715680 /* JSONStandardTypeConversions.swift in Sources */,
 				9B1A38532332AF6F00325FB4 /* String+SHA.swift in Sources */,
 				9BEDC79E22E5D2CF00549BF6 /* RequestCreator.swift in Sources */,
+				9BE071AD2368D08700FA5952 /* Collection+Helpers.swift in Sources */,
 				9FA6F3681E65DF4700BF8D73 /* GraphQLResultAccumulator.swift in Sources */,
 				9FF90A651DDDEB100034C3B6 /* GraphQLExecutor.swift in Sources */,
 				9FC750611D2A59C300458D91 /* GraphQLOperation.swift in Sources */,
diff --git a/Sources/Apollo/Bundle+Helpers.swift b/Sources/Apollo/Bundle+Helpers.swift
index 6730fa1376..e87f2481e8 100644
--- a/Sources/Apollo/Bundle+Helpers.swift
+++ b/Sources/Apollo/Bundle+Helpers.swift
@@ -1,11 +1,3 @@
-//
-//  Bundle+Helpers.swift
-//  Apollo
-//
-//  Created by Ellen Shapiro on 10/23/19.
-//  Copyright © 2019 Apollo GraphQL. All rights reserved.
-//
-
 import Foundation
 
 extension Bundle {
diff --git a/Sources/Apollo/Collection+Helpers.swift b/Sources/Apollo/Collection+Helpers.swift
new file mode 100644
index 0000000000..eef0020680
--- /dev/null
+++ b/Sources/Apollo/Collection+Helpers.swift
@@ -0,0 +1,65 @@
+import Foundation
+
+// MARK: - Emptiness + Optionality
+
+extension Collection {
+  
+  /// Convenience helper to make `guard` statements more readable
+  ///
+  /// - returns: `true` if the collection has contents.
+  var isNotEmpty: Bool {
+    return !self.isEmpty
+  }
+}
+
+extension Optional where Wrapped: Collection {
+  
+  /// - returns: `true` if the collection is empty or nil
+  var isEmptyOrNil: Bool {
+    switch self {
+    case .none:
+      return true
+    case .some(let collection):
+      return collection.isEmpty
+    }
+  }
+  
+  /// - returns: `true` if the collection is non-nil AND has contents.
+  var isNotEmpty: Bool {
+    switch self {
+    case .none:
+      return false
+    case .some(let collection):
+      return collection.isNotEmpty
+    }
+  }
+}
+
+// MARK: - Unzipping
+// MARK: Arrays of tuples to tuples of arrays
+
+public func unzip<Element1, Element2>(_ array: [(Element1, Element2)]) -> ([Element1], [Element2]) {
+  var array1: [Element1] = []
+  var array2: [Element2] = []
+  
+  for element in array {
+    array1.append(element.0)
+    array2.append(element.1)
+  }
+  
+  return (array1, array2)
+}
+
+public func unzip<Element1, Element2, Element3>(_ array: [(Element1, Element2, Element3)]) -> ([Element1], [Element2], [Element3]) {
+  var array1: [Element1] = []
+  var array2: [Element2] = []
+  var array3: [Element3] = []
+  
+  for element in array {
+    array1.append(element.0)
+    array2.append(element.1)
+    array3.append(element.2)
+  }
+  
+  return (array1, array2, array3)
+}
diff --git a/Sources/Apollo/Collections.swift b/Sources/Apollo/Collections.swift
deleted file mode 100644
index 6ad5532b1a..0000000000
--- a/Sources/Apollo/Collections.swift
+++ /dev/null
@@ -1,94 +0,0 @@
-public extension Dictionary {
-  static func += (lhs: inout Dictionary, rhs: Dictionary) {
-    lhs.merge(rhs) { (_, new) in new }
-  }
-}
-
-extension Dictionary {
-  init<S: Sequence>(_ entries: S) where S.Iterator.Element == Element {
-    self = Dictionary(minimumCapacity: entries.underestimatedCount)
-    for (key, value) in entries {
-      self[key] = value
-    }
-  }
-}
-
-struct GroupedSequence<Key: Equatable, Value> {
-  private(set) var keys: [Key] = []
-  fileprivate var groupsForKeys: [[Value]] = []
-  
-  mutating func append(value: Value, forKey key: Key) -> (Int, Int) {
-    if let index = keys.firstIndex(where: { $0 == key }) {
-      groupsForKeys[index].append(value)
-      return (index, groupsForKeys[index].endIndex - 1)
-    } else {
-      keys.append(key)
-      groupsForKeys.append([value])
-      return (keys.endIndex - 1, 0)
-    }
-  }
-}
-
-extension GroupedSequence: Sequence {
-  func makeIterator() -> GroupedSequenceIterator<Key, Value> {
-    return GroupedSequenceIterator(base: self)
-  }
-}
-
-struct GroupedSequenceIterator<Key: Equatable, Value>: IteratorProtocol {
-  private var base: GroupedSequence<Key, Value>
-  
-  private var keyIterator: EnumeratedSequence<Array<Key>>.Iterator
-  
-  init(base: GroupedSequence<Key, Value>) {
-    self.base = base
-    keyIterator = base.keys.enumerated().makeIterator()
-  }
-  
-  mutating func next() -> (Key, [Value])? {
-    if let (index, key) = keyIterator.next() {
-      let values = base.groupsForKeys[index]
-      return (key, values)
-    } else {
-      return nil
-    }
-  }
-}
-
-public func unzip<Element1, Element2>(_ array: [(Element1, Element2)]) -> ([Element1], [Element2]) {
-  var array1: [Element1] = []
-  var array2: [Element2] = []
-  
-  for element in array {
-    array1.append(element.0)
-    array2.append(element.1)
-  }
-  
-  return (array1, array2)
-}
-
-public func unzip<Element1, Element2, Element3>(_ array: [(Element1, Element2, Element3)]) -> ([Element1], [Element2], [Element3]) {
-  var array1: [Element1] = []
-  var array2: [Element2] = []
-  var array3: [Element3] = []
-  
-  for element in array {
-    array1.append(element.0)
-    array2.append(element.1)
-    array3.append(element.2)
-  }
-  
-  return (array1, array2, array3)
-}
-
-public func unzip<Element>(_ array: [[Element]], count: Int) -> [[Element]] {  
-  var unzippedArray: [[Element]] = Array(repeating: [], count: count)
-  
-  for valuesForElement in array {
-    for (index, value) in valuesForElement.enumerated() {
-      unzippedArray[index].append(value)
-    }
-  }
-  
-  return unzippedArray
-}
diff --git a/Sources/Apollo/Dictionary+Helpers.swift b/Sources/Apollo/Dictionary+Helpers.swift
new file mode 100644
index 0000000000..27832500f9
--- /dev/null
+++ b/Sources/Apollo/Dictionary+Helpers.swift
@@ -0,0 +1,14 @@
+public extension Dictionary {
+  static func += (lhs: inout Dictionary, rhs: Dictionary) {
+    lhs.merge(rhs) { (_, new) in new }
+  }
+}
+
+extension Dictionary {
+  init<S: Sequence>(_ entries: S) where S.Iterator.Element == Element {
+    self = Dictionary(minimumCapacity: entries.underestimatedCount)
+    for (key, value) in entries {
+      self[key] = value
+    }
+  }
+}
diff --git a/Sources/Apollo/DispatchQueue+Optional.swift b/Sources/Apollo/DispatchQueue+Optional.swift
index 38e0bcf031..0847c53dea 100644
--- a/Sources/Apollo/DispatchQueue+Optional.swift
+++ b/Sources/Apollo/DispatchQueue+Optional.swift
@@ -1,11 +1,3 @@
-//
-//  DispatchQueue+Optional.swift
-//  Apollo
-//
-//  Created by Ellen Shapiro on 8/13/19.
-//  Copyright © 2019 Apollo GraphQL. All rights reserved.
-//
-
 import Foundation
 
 public extension DispatchQueue {
diff --git a/Sources/Apollo/GraphQLSelectionSet.swift b/Sources/Apollo/GraphQLSelectionSet.swift
index 6be1219a5e..67c1b51d1d 100644
--- a/Sources/Apollo/GraphQLSelectionSet.swift
+++ b/Sources/Apollo/GraphQLSelectionSet.swift
@@ -51,9 +51,11 @@ public struct GraphQLField: GraphQLSelection {
   }
   
   func cacheKey(with variables: [String: JSONEncodable]?) throws -> String {
-    if let argumentValues = try arguments?.evaluate(with: variables), !argumentValues.isEmpty {
-      let argumentsKey = orderIndependentKey(for: argumentValues)
-      return "\(name)(\(argumentsKey))"
+    if
+      let argumentValues = try arguments?.evaluate(with: variables),
+      argumentValues.isNotEmpty {
+        let argumentsKey = orderIndependentKey(for: argumentValues)
+        return "\(name)(\(argumentsKey))"
     } else {
       return name
     }
diff --git a/Sources/Apollo/GroupedSequence.swift b/Sources/Apollo/GroupedSequence.swift
new file mode 100644
index 0000000000..231e759105
--- /dev/null
+++ b/Sources/Apollo/GroupedSequence.swift
@@ -0,0 +1,41 @@
+struct GroupedSequence<Key: Equatable, Value> {
+  private(set) var keys: [Key] = []
+  fileprivate var groupsForKeys: [[Value]] = []
+  
+  mutating func append(value: Value, forKey key: Key) -> (Int, Int) {
+    if let index = keys.firstIndex(where: { $0 == key }) {
+      groupsForKeys[index].append(value)
+      return (index, groupsForKeys[index].endIndex - 1)
+    } else {
+      keys.append(key)
+      groupsForKeys.append([value])
+      return (keys.endIndex - 1, 0)
+    }
+  }
+}
+
+extension GroupedSequence: Sequence {
+  func makeIterator() -> GroupedSequenceIterator<Key, Value> {
+    return GroupedSequenceIterator(base: self)
+  }
+}
+
+struct GroupedSequenceIterator<Key: Equatable, Value>: IteratorProtocol {
+  private var base: GroupedSequence<Key, Value>
+  
+  private var keyIterator: EnumeratedSequence<Array<Key>>.Iterator
+  
+  init(base: GroupedSequence<Key, Value>) {
+    self.base = base
+    keyIterator = base.keys.enumerated().makeIterator()
+  }
+  
+  mutating func next() -> (Key, [Value])? {
+    if let (index, key) = keyIterator.next() {
+      let values = base.groupsForKeys[index]
+      return (key, values)
+    } else {
+      return nil
+    }
+  }
+}
diff --git a/Sources/Apollo/HTTPNetworkTransport.swift b/Sources/Apollo/HTTPNetworkTransport.swift
index 195432e538..1cfdc04ff9 100644
--- a/Sources/Apollo/HTTPNetworkTransport.swift
+++ b/Sources/Apollo/HTTPNetworkTransport.swift
@@ -47,6 +47,7 @@ public protocol HTTPNetworkTransportTaskCompletedDelegate: HTTPNetworkTransportD
 
 // MARK: -
 
+/// Methods which will be called if an error is receieved at the network level.
 public protocol HTTPNetworkTransportRetryDelegate: HTTPNetworkTransportDelegate {
   
   /// Called when an error has been received after a request has been sent to the server to see if an operation should be retried or not.
@@ -65,12 +66,19 @@ public protocol HTTPNetworkTransportRetryDelegate: HTTPNetworkTransportDelegate
                         retryHandler: @escaping (_ shouldRetry: Bool) -> Void)
 }
 
-/// Methods which will be called after some kind of response has been received and it contains GraphQLErrors
-public protocol HTTPNetworkTransportGraphQLErrorDelegate: HTTPNetworkTransportDelegate {
+// MARK: -
 
+/// Methods which will be called after some kind of response has been received and it contains GraphQLErrors.
+public protocol HTTPNetworkTransportGraphQLErrorDelegate: HTTPNetworkTransportDelegate {
 
   /// Called when response contains one or more GraphQL errors.
-  /// NOTE: Don't just call the `retryHandler` with `true` all the time, or you can potentially wind up in an infinite loop of errors
+  ///
+  /// NOTE: The mere presence of a GraphQL error does not necessarily mean a request failed!
+  ///       GraphQL is design to allow partial success/failures to return, so make sure
+  ///       you're validating the *type* of error you're getting in this before deciding whether to retry or not.
+  ///
+  /// ALSO NOTE: Don't just call the `retryHandler` with `true` all the time, or you can
+  ///            potentially wind up in an infinite loop of errors
   ///
   /// - Parameters:
   ///   - networkTransport: The network transport which received the error
@@ -79,7 +87,6 @@ public protocol HTTPNetworkTransportGraphQLErrorDelegate: HTTPNetworkTransportDe
   func networkTransport(_ networkTransport: HTTPNetworkTransport, receivedGraphQLErrors errors: [GraphQLError], retryHandler: @escaping (_ shouldRetry: Bool) -> Void)
 }
 
-
 // MARK: -
 
 /// A network transport that uses HTTP POST requests to send GraphQL operations to a server, and that uses `URLSession` as the networking implementation.
@@ -224,9 +231,10 @@ public class HTTPNetworkTransport {
                                                         files: [GraphQLFile]?,
                                                         response: GraphQLResponse<Operation>,
                                                         completionHandler: @escaping (_ result: Result<GraphQLResponse<Operation>, Error>) -> Void) {
-    guard let delegate = self.delegate as? HTTPNetworkTransportGraphQLErrorDelegate,
+    guard
+      let delegate = self.delegate as? HTTPNetworkTransportGraphQLErrorDelegate,
       let graphQLErrors = response.parseErrorsOnlyFast(),
-      !graphQLErrors.isEmpty else {
+      graphQLErrors.isNotEmpty else {
         completionHandler(.success(response))
         return
     }
@@ -379,16 +387,18 @@ public class HTTPNetworkTransport {
       }
     case .POST:
       do {
-        if let files = files, !files.isEmpty {
-          let formData = try requestCreator.requestMultipartFormData(
-            for: operation,
-            files: files,
-            sendOperationIdentifiers: self.sendOperationIdentifiers,
-            serializationFormat: self.serializationFormat,
-            manualBoundary: nil)
-          
-          request.setValue("multipart/form-data; boundary=\(formData.boundary)", forHTTPHeaderField: "Content-Type")
-          request.httpBody = try formData.encode()
+        if
+          let files = files,
+          files.isNotEmpty {
+            let formData = try requestCreator.requestMultipartFormData(
+              for: operation,
+              files: files,
+              sendOperationIdentifiers: self.sendOperationIdentifiers,
+              serializationFormat: self.serializationFormat,
+              manualBoundary: nil)
+            
+            request.setValue("multipart/form-data; boundary=\(formData.boundary)", forHTTPHeaderField: "Content-Type")
+            request.httpBody = try formData.encode()
         } else {
           request.httpBody = try serializationFormat.serialize(value: body)
         }
diff --git a/Sources/Apollo/Utilities.swift b/Sources/Apollo/HTTPURLResponse+Helpers.swift
similarity index 82%
rename from Sources/Apollo/Utilities.swift
rename to Sources/Apollo/HTTPURLResponse+Helpers.swift
index 4778c3e0d3..128e7f60ca 100644
--- a/Sources/Apollo/Utilities.swift
+++ b/Sources/Apollo/HTTPURLResponse+Helpers.swift
@@ -15,9 +15,3 @@ extension HTTPURLResponse {
     return String.Encoding(rawValue: CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding(encodingName as CFString)))
   }
 }
-
-public protocol Matchable {
-  associatedtype Base
-  static func ~=(pattern: Self, value: Base) -> Bool
-}
-
diff --git a/Sources/Apollo/Matchable.swift b/Sources/Apollo/Matchable.swift
new file mode 100644
index 0000000000..d09ca9653d
--- /dev/null
+++ b/Sources/Apollo/Matchable.swift
@@ -0,0 +1,14 @@
+//
+//  Matchable.swift
+//  Apollo
+//
+//  Created by Ellen Shapiro on 10/29/19.
+//  Copyright © 2019 Apollo GraphQL. All rights reserved.
+//
+
+import Foundation
+
+public protocol Matchable {
+  associatedtype Base
+  static func ~=(pattern: Self, value: Base) -> Bool
+}
diff --git a/Sources/Apollo/Promise.swift b/Sources/Apollo/Promise.swift
index c838279c94..ed778e033a 100644
--- a/Sources/Apollo/Promise.swift
+++ b/Sources/Apollo/Promise.swift
@@ -226,8 +226,10 @@ final class Promise<Value> {
     lock.withLock {
       // If the promise has been resolved and there are no existing result handlers,
       // there is no need to append the handler to the array first.
-      if case .resolved(let result) = state, resultHandlers.isEmpty {
-        handler(result)
+      if
+        case .resolved(let result) = state,
+        resultHandlers.isEmpty {
+          handler(result)
       } else {
         resultHandlers.append(handler)
       }
diff --git a/Sources/Apollo/String+SHA.swift b/Sources/Apollo/String+SHA.swift
index a1d3c5b930..27912773a1 100644
--- a/Sources/Apollo/String+SHA.swift
+++ b/Sources/Apollo/String+SHA.swift
@@ -1,11 +1,3 @@
-//
-//  String+SHA.swift
-//  Apollo
-//
-//  Created by Ellen Shapiro on 9/18/19.
-//  Copyright © 2019 Apollo GraphQL. All rights reserved.
-//
-
 import Foundation
 import CommonCrypto