async def container_val(self, elem, container_type, params=None):
if hasattr(container_type, "<STR_LIT>"):<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>if self.writing:<EOL><INDENT>return await self._dump_container_val(<EOL>self.iobj, elem, container_type, params<EOL>)<EOL><DEDENT>else:<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>
Single cont value
:param elem:
:param container_type:
:param params:
:return: