@classmethod
def strip_off_start(cls, s: str, pre: str):
    """
		Strips the full string `pre` from the start of `str`.
		See `Tools.strip_off` for more info.
		"""
    assert isinstance(pre, str), '{} is not a string'.format(pre)
    if s.startswith(pre):
        s = s[len(pre):]
    return s
