def sort(self, **kwargs):
query = {}<EOL>for field in kwargs:<EOL><INDENT>query[field] = kwargs[field]<EOL><DEDENT>self._q.append({'<STR_LIT>': query})<EOL>return self<EOL>
Adds a sort stage to aggregation query
:param kwargs: Specifies the field(s) to sort by and the respective sort order.
:return: The current object