async def _dump_container_val(self, writer, elem, container_type, params=None):
elem_type = container_elem_type(container_type, params)<EOL>await self.dump_field(writer, elem, elem_type, params[<NUM_LIT:1>:] if params else None)<EOL>
Single elem dump
:param writer:
:param elem:
:param container_type:
:param params:
:return: