Refactor after code review

lib/tasks/user_username_change.rake

@@ -16,16 +16,12 @@ namespace :cartodb do
       user.save_metadata
 
       # Rename user and database schema
-        user.in_database({as: :superuser}) do |db|
+      user.in_database(as: :superuser) { |db|
         db.run("ALTER SCHEMA \"#{args[:old_username]}\" RENAME TO \"#{args[:new_username]}\";")
-        end
+      }
 
       # Regenerate API Keys
-        user.carto_user.api_keys.each { |api_key|
-          if api_key.master?
-            api_key.regenerate_token!
-          end
-        }
+      user.carto_user.api_keys.find(&:master?).try(:regenerate_token!)
 
       # Fix map analysis
       user.carto_user.tables.each do |table|
@@ -40,11 +36,7 @@ namespace :cartodb do
       end
 
       # Fix public maps
-        Carto::Visualization.where(type: 'derived', user: user.carto_user).each { |visualization|
-          if visualization.published?
-            visualization.create_mapcap!
-          end
-        }
+      Carto::Visualization.where(type: 'derived', user: user.carto_user).select(&:published?).each { |visualization| visualization.create_mapcap! }
     end
   end
 end