code: def merge(directory=None, revisions='', message=None, branch_label=None,
            rev_id=None):
      
      if alembic_version >= (0, 7, 0):
          config = current_app.extensions['migrate'].migrate.get_config(
              directory)
          command.merge(config, revisions, message=message,
                        branch_label=branch_label, rev_id=rev_id)
      else:
          raise RuntimeError('Alembic 0.7.0 or greater is required')
docs: Merge two revisions together.  Creates a new migration file