code: def get_source(self, index, doc_type, id, **query_params):
          
          self._es_parser.is_not_empty_params(index, doc_type, id)
          path = self._es_parser.make_path(index, doc_type, id, EsMethods.SOURCE)
          result = yield self._perform_request(HttpMethod.GET,
                                               path,
                                               params=query_params)
          returnValue(result)
docs: Get the _source of the document
          `<http://www.elastic.co/guide/en/elasticsearch/reference/current/docs-get.html>`_
          :param index: the index name
          :param doc_type: the document type
          :param id: the id of the doc type
          :arg _source: True or false to return the _source field or not, or a
              list of fields to return
          :arg _source_exclude: A list of fields to exclude from the returned
              _source field
          :arg _source_include: A list of fields to extract and return from the
              _source field
          :arg parent: The ID of the parent document
          :arg preference: Specify the node or shard the operation should be
              performed on (default: random)
          :arg realtime: Specify whether to perform the operation in realtime or
              search mode
          :arg refresh: Refresh the shard containing the document before
              performing the operation
          :arg routing: Specific routing value
          :arg version: Explicit version number for concurrency control
          :arg version_type: Specific version type, valid choices are: 'internal',
              'external', 'external_gte', 'force'