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 usage_iter(root):
    root = os.path.abspath(root)
    root_size = get_folder_size(root)
    root_string = "{0}\n{1}".format(root, root_size)
    yield [root_string, None, root_size]