Compare two versions

    :param ver1: version string 1
    :param ver2: version string 2
    :return: The return value is negative if ver1 < ver2,
             zero if ver1 == ver2 and strictly positive if ver1 > ver2
    :rtype: int

    >>> import semver
    >>> semver.compare("1.0.0", "2.0.0")
    -1
    >>> semver.compare("2.0.0", "1.0.0")
    1
    >>> semver.compare("2.0.0", "2.0.0")
    0

def compare(ver1, ver2):
    """Compare two versions

    :param ver1: version string 1
    :param ver2: version string 2
    :return: The return value is negative if ver1 < ver2,
             zero if ver1 == ver2 and strictly positive if ver1 > ver2
    :rtype: int

    >>> import semver
    >>> semver.compare("1.0.0", "2.0.0")
    -1
    >>> semver.compare("2.0.0", "1.0.0")
    1
    >>> semver.compare("2.0.0", "2.0.0")
    0
    """

    v1, v2 = parse(ver1), parse(ver2)

    return _compare_by_keys(v1, v2)