def _match_first_key(skip_first_axis=None, feature=""):
    """Helper function to match and remove skip_first_axis from feature

    :param skip_first_axis: True or string. if set, ignore first axis of input histogram(s)
    :param feature: input feature
    :return: match and (rest of) feature
    """
    assert isinstance(feature, str)
    karr = feature.split(":")
    begin = karr[0]
    rest_key = ":".join(karr[1:])
    if isinstance(skip_first_axis, bool):
        return skip_first_axis, rest_key if skip_first_axis else feature
    elif isinstance(skip_first_axis, str) and len(skip_first_axis) > 0:
        match = begin == skip_first_axis
        return match, rest_key if match else feature
    return False, feature