def __init__(self, name, filename=None):
        self.name = name
        super(NamedRequirements, self).__init__(filename=filename)
def json_usage(root):
    root = os.path.abspath(root)
    result = [['Path', 'Parent', 'Usage']]
    result.extend(entry for entry in usage_iter(root))
    return json.dumps(result)