def METHOD_NAME(self):
    """ Get a dictionary of label number to string pairs representing all labels associated with this number
        on the model labels.
    """
    model_labels = self._get_task_property('execution.model_labels')
    label_getter = operator.itemgetter(0)
    num_getter = operator.itemgetter(1)
    groups = list(itertools.groupby(sorted(model_labels.items(), key=num_getter), key=num_getter))
    if any(len(set(label_getter(x) for x in group)) > 1 for _, group in groups):
        raise ValueError("Multiple labels mapped to same model index not supported")
    return {key: ','.join(label_getter(x) for x in group) for key, group in groups}