code: def current(directory=None, verbose=False, head_only=False):
      
      config = current_app.extensions['migrate'].migrate.get_config(directory)
      if alembic_version >= (0, 7, 0):
          command.current(config, verbose=verbose, head_only=head_only)
      else:
          command.current(config)
docs: Display the current revision for each database.