different way of specifying json & csv. Maybe this is cleaner?

Rakefile

@@ -345,10 +345,8 @@ desc 'Clear Chilled Water Storage Scenario'
 task :clear_chilled_water_storage, [:json, :csv] do |t, args|
   puts 'Clearing Chilled Water Storage Scenario...'
 
-  json = args[:json]
-  csv = args[:csv]
-  json = 'example_project_combined.json' if json.nil?
-  csv = 'chilled_water_storage_scenario.csv' if csv.nil?
+  json = args[:json] or 'example_project_combined.json'
+  csv = args[:csv] or 'chilled_water_storage_scenario.csv'
 
   chilled_water_storage_scenario(json, csv).clear
 end
@@ -357,10 +355,8 @@ desc 'Run Chilled Water Storage Scenario'
 task :run_chilled_water_storage, [:json, :csv] do |t, args|
   puts 'Running Chilled Water Storage Scenario...'
 
-  json = args[:json]
-  csv = args[:csv]
-  json = 'example_project_combined.json' if json.nil?
-  csv = 'chilled_water_storage_scenario.csv' if csv.nil?
+  json = args[:json] or 'example_project_combined.json'
+  csv = args[:csv] or 'chilled_water_storage_scenario.csv'
 
   configure_project
 
@@ -372,10 +368,8 @@ desc 'Post Process Chilled Water Storage Scenario'
 task :post_process_chilled_water_storage, [:json, :csv] do |t, args|
   puts 'Post Processing Chilled Water Storage Scenario...'
 
-  json = args[:json]
-  csv = args[:csv]
-  json = 'example_project_combined.json' if json.nil?
-  csv = 'chilled_water_storage_scenario.csv' if csv.nil?
+  json = args[:json] or 'example_project_combined.json'
+  csv = args[:csv] or 'chilled_water_storage_scenario.csv'
 
   default_post_processor = URBANopt::Scenario::ScenarioDefaultPostProcessor.new(chilled_water_storage_scenario(json, csv))
   scenario_result = default_post_processor.run