def _parse_version(raw):
    """
    Given a colon delimited plugin string, parse a (name, version) tuple.

    >>> _parse_version("git:2.3.5")
    ('git', '2.3.5')
    >>> _parse_version("git")
    ('git', None)
    """
    tmp = raw.split(':')
    name = tmp[0]
    version = None if len(tmp) == 1 else tmp[1]
    return (name, version)