old_contents: from django.db import transaction
  
  
  class WarehouseTable(object):
  
      @classmethod
      def commit(cls, start_datetime, end_datetime):
          raise NotImplementedError
  
      @classmethod
      def dependencies(cls):
          '''Returns a list of slugs that the warehouse table is dependent on'''
          raise NotImplementedError
  
new_contents: 
  
  class WarehouseTable(object):
  
      @classmethod
      def commit(cls, start_datetime, end_datetime):
          raise NotImplementedError
  
      @classmethod
      def dependencies(cls):
          '''Returns a list of slugs that the warehouse table is dependent on'''
          raise NotImplementedError
  
subject: Remove unused import