'Return a list of fileids that make up this corpus.  If
``vnclass_ids`` is specified, then return the fileids that make
up the specified verbnet class(es).'

def fileids(self, vnclass_ids=None):

    if (vnclass_ids is None):
        return self._fileids
    elif isinstance(vnclass_ids, string_types):
        return [self._class_to_fileid[self.longid(vnclass_ids)]]
    else:
        return [self._class_to_fileid[self.longid(vnclass_id)] for vnclass_id in vnclass_ids]
