def METHOD_NAME(callback):
    """
    Return the callback namedtuple to represent the specified callback.
    Args:
        callback (dict): the callback definition.
    The callback given in argument should be a dictionary containing
    the expected fields for a callback (code, author, valid...).
    """
    if "obj" not in callback:
        callback["obj"] = None
    if "name" not in callback:
        callback["name"] = "unknown"
    if "number" not in callback:
        callback["number"] = -1
    if "code" not in callback:
        callback["code"] = ""
    if "author" not in callback:
        callback["author"] = None
    if "valid" not in callback:
        callback["valid"] = False
    if "parameters" not in callback:
        callback["parameters"] = ""
    if "created_on" not in callback:
        callback["created_on"] = None
    if "updated_by" not in callback:
        callback["updated_by"] = None
    if "updated_on" not in callback:
        callback["updated_on"] = None
    return Callback(**callback)