def METHOD_NAME(self, return_val):
    """Before the types and attrs get passed to the
    importer they need to be altered by converting lists to
    sets, etc.
    """
    types, attrs = return_val
    _attrs = {}
    # Get rid of defaultdict.
    for k, v in attrs.items():
        # Skip empties.
        if not v:
            continue
        else:
            v = filter(None, v)
        # Get rid of sets.
        if isinstance(v, set):
            v = list(v)
        # Some vals should be strings, not seqs.
        if k == "actor" and len(v) == 1:
            v = v.pop()
        _attrs[k] = v
    return types, _attrs