code: def _call_migrate(self, module, connection_param):
          
          args = [connection_param]
          spec = inspect.getargspec(module.migrate)
          if len(spec.args) == 2:
              args.append(self.db_config)
          return module.migrate(*args)
docs: Subclasses should call this method instead of `module.migrate` directly,
          to support `db_config` optional argument.