def identify_nested_items(complete_list):
    """Identify nested and non-nested two-element tuples in a list.

    :param complete_list: List of tuples that will be evaluated.
    :type complete_list: list
    :returns:
        tuple (not_nested_set, nested_set)
        WHERE
        not_nested_set(set) is a set of non-nested tuples.
        nested_set(set) is a set of nested tuples.
    :rtype: tuple
    """
    not_nested_set = set()
    nested_set = set()
    return not_nested_set, nested_set
