Unregister a matcher (or alias) from the registry

def unregister(matcher):
    """ Unregister a matcher (or alias) from the registry
    """
    # If it's a string handle it like an alias
    if isinstance(matcher, text_types) and matcher in matchers:
        matcher = matchers[matcher]

    # Find all aliases associated to the matcher
    aliases = [k for k, v in matchers.iteritems() if v == matcher]
    for alias in aliases:
        del matchers[alias]
        # Clean up the normalized versions
        norms = [k for k, v in normalized.iteritems() if v == alias]
        for norm in norms:
            del normalized[norm]

    # Remove help docstring
    if matcher in helpmatchers:
        del helpmatchers[matcher]

    return len(aliases) > 0