def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def mkhead(repo: 'Repo', path: PathLike) -> 'Head':
    """:return: New branch/head instance"""
    return git.Head(repo, git.Head.to_full_path(path))