def container_elem_type(container_type, params):
elem_type = params[<NUM_LIT:0>] if params else None<EOL>if elem_type is None:<EOL><INDENT>elem_type = container_type.ELEM_TYPE<EOL><DEDENT>return elem_type<EOL>
Returns container element type

:param container_type:
:param params:
:return: