def p_route_io(self, p):
if len(p) > <NUM_LIT:6>:<EOL><INDENT>p[<NUM_LIT:0>] = (p[<NUM_LIT:2>], p[<NUM_LIT:4>], p[<NUM_LIT:6>])<EOL><DEDENT>else:<EOL><INDENT>p[<NUM_LIT:0>] = (p[<NUM_LIT:2>], p[<NUM_LIT:4>], None)<EOL><DEDENT>
route_io : LPAR type_ref COMMA type_ref RPAR
                    | LPAR type_ref COMMA type_ref COMMA type_ref RPAR