def _key_case(arg: str):
    """Convert string to key_case.

    Only the non-prefix part of curies is retained
    all spaces and _ removed
    then all lowercased
    """
    tmp = arg.split(':')[-1]
    tmp = ''.join(tmp.split(' '))
    tmp = ''.join(tmp.split('_'))
    tmp = ''.join(tmp.split(','))
    tmp = tmp.lower()
    return tmp