def METHOD_NAME(self, element_tree, val_name):
    """
    Returns true if either all or none of the enum items
    contain a given value
    """
    has_value = 0
    total = 0
    for enum_item in element_tree.iter():
        if enum_item.tag == "item":
            total += 1
            if val_name in enum_item.keys():
                has_value += 1
    is_consistent = True
    if not has_value in (0, total):
        is_consistent = False
    return is_consistent