def __init__(self, func, name):
        # type: (Callable, str) -> None
        self.name = name
        try:
            self.arg_pos = self._getargnames(func).index(name)
        except __HOLE__:
            # Not a positional parameter
            self.arg_pos = None
dataset/ETHPy150Open tornadoweb/tornado/tornado/util.py/ArgReplacer.__init__