def METHOD_NAME(self, item):
    """Returns the 1-based numerical index of the item in the container"""
    pred = self.graph.predicates(self.uri, item)
    if not pred:
        raise ValueError("%s is not in %s" % (item, "container"))
    li_index = URIRef(str(RDF) + "_")
    i = None
    for p in pred:
        i = int(p.replace(li_index, ""))
    return i