def clean_semver(cls, version_spec):
        return re.sub(r"([<>=~])\s+?v?", "\\1", version_spec, re.IGNORECASE)
def test_regex_good_input():
    cases = (
        '123',
        '1234567890',
        '00000',
    )

    num_only = inputs.regex(r'^[0-9]+$')

    for value in cases:
        yield assert_equal, num_only(value), value