def no_dup_dict(url_set):
    """Create a dictionary from list of lists.

    This function expects a list of 2-tuples of the form (key, value),
    where key becomes the dictionary key and value becomes the associated
    value. In the event that there are more than 1 2-tuples with the same
    key, no entries are made into the dictionary.
    """
    attr_dict = {}
    del_list = []
    for entity, attribute in url_set:
        if entity in attr_dict:
            del_list.append(entity)
        else:
            attr_dict[entity] = attribute
    # For all the entities that had duplicates, delete the dict entry.
    for entity in set(del_list):
        del(attr_dict[entity])
    return attr_dict