old_contents: from contextlib import closing
  from operator import contains
  from functools import partial
  
  from minerva.util import k, identity
  from minerva.directory import EntityType
  from minerva.storage import Engine
  from minerva.storage.trend import TableTrendStore
  
  
  class TrendEngine(Engine):
      @staticmethod
      def store_cmd(package, filter_package=k(identity)):
          """
          Return a function to bind a data source to the store command.
  
          :param package: A DataPackageBase subclass instance
          :param filter_package: (TableTrendStore) -> (DataPackage) -> DataPackage
          :return: function that can bind a data source to the store command
          :rtype: (data_source) -> (conn) -> None
          """
          def bind_data_source(data_source):
              def execute(conn):
                  entity_type_name = package.entity_type_name()
  
                  with closing(conn.cursor()) as cursor:
                      entity_type = EntityType.get_by_name(entity_type_name)(
                          cursor
                      )
  
                      trend_store = TableTrendStore.get(
                          data_source, entity_type, package.granularity
                      )(cursor)
  
                  trend_store.store(
                      filter_package(trend_store)(package)
                  ).run(conn)
  
              return execute
  
          return bind_data_source
  
  
  def filter_existing_trends(trend_store):
      existing_trend_names = {trend.name for trend in trend_store.trends}
  
      def f(package):
          return package.filter_trends(partial(contains, existing_trend_names))
  
      return f
  
new_contents: from contextlib import closing
  from operator import contains
  from functools import partial
  
  from minerva.util import k, identity
  from minerva.directory import EntityType
  from minerva.storage import Engine
  from minerva.storage.trend import TableTrendStore
  
  
  class TrendEngine(Engine):
      @staticmethod
      def store_cmd(package, filter_package=k(identity)):
          """
          Return a function to bind a data source to the store command.
  
          :param package: A DataPackageBase subclass instance
          :param filter_package: (TableTrendStore) -> (DataPackage) -> DataPackage
          :return: function that binds a data source to the store command
          :rtype: (data_source) -> (conn) -> None
          """
          def bind_data_source(data_source):
              def execute(conn):
                  entity_type_name = package.entity_type_name()
  
                  with closing(conn.cursor()) as cursor:
                      entity_type = EntityType.get_by_name(entity_type_name)(
                          cursor
                      )
  
                      trend_store = TableTrendStore.get(
                          data_source, entity_type, package.granularity
                      )(cursor)
  
                  trend_store.store(
                      filter_package(trend_store)(package)
                  ).run(conn)
  
              return execute
  
          return bind_data_source
  
  
  def filter_existing_trends(trend_store):
      existing_trend_names = {trend.name for trend in trend_store.trends}
  
      def f(package):
          return package.filter_trends(partial(contains, existing_trend_names))
  
      return f
  
subject: Improve comment