def unregister_type(item_type):
if item_type not in Pipe.pipe_item_types:<EOL><INDENT>return<EOL><DEDENT>del Pipe.pipe_item_types[item_type]<EOL>
Unregister data type from Pipe class. Check Pipe.__or__ and Pipe.__ror__ for
    detail.

    :param item_type: The type of data object which used in pipe cascading.