Remove None from param types and add (Optional).

This runs a script to remove None from the types for parameters, and
added (Optional) to the description. Does not pass lint due to some
too-long lines. I will clean those up manually.

See:
googleapis/google-cloud-python#2580 (review)

google/cloud/datastore/connection.py

@@ -569,8 +569,8 @@ def commit(self, project, request, transaction_id):
         :type request: :class:`._generated.datastore_pb2.CommitRequest`
         :param request: The protobuf with the mutations being committed.
 
-        :type transaction_id: str or None
-        :param transaction_id: The transaction ID returned from
+        :type transaction_id: str
+        :param transaction_id: (Optional) The transaction ID returned from
                                :meth:`begin_transaction`.  Non-transactional
                                batches must pass ``None``.
 

google/cloud/datastore/key.py

@@ -388,8 +388,8 @@ def _validate_project(project, parent):
     :type project: str
     :param project: A project.
 
-    :type parent: :class:`google.cloud.datastore.key.Key` or ``NoneType``
-    :param parent: The parent of the key or ``None``.
+    :type parent: :class:`google.cloud.datastore.key.Key`
+    :param parent: (Optional) The parent of the key or ``None``.
 
     :rtype: str
     :returns: The ``project`` passed in, or implied from the environment.

google/cloud/datastore/query.py

@@ -38,12 +38,12 @@ class Query(object):
     :param project: The project associated with the query.  If not passed,
                     uses the client's value.
 
-    :type namespace: str or None
-    :param namespace: The namespace to which to restrict results.  If not
+    :type namespace: str
+    :param namespace: (Optional) The namespace to which to restrict results.  If not
                       passed, uses the client's value.
 
-    :type ancestor: :class:`google.cloud.datastore.key.Key` or None
-    :param ancestor: key of the ancestor to which this query's results are
+    :type ancestor: :class:`google.cloud.datastore.key.Key`
+    :param ancestor: (Optional) key of the ancestor to which this query's results are
                      restricted.
 
     :type filters: sequence of (property_name, operator, value) tuples
@@ -327,8 +327,8 @@ def fetch(self, limit=None, offset=0, start_cursor=None, end_cursor=None,
           >>> list(query.fetch(1))
           [<Entity object>]
 
-        :type limit: int or None
-        :param limit: An optional limit passed through to the iterator.
+        :type limit: int
+        :param limit: (Optional) An optional limit passed through to the iterator.
 
         :type offset: int
         :param offset: An optional offset passed through to the iterator.