def _resolve(self, fileids, categories):
        if fileids is not None or categories is not None:
            raise ValueError('Specify fileids or categories, not both')
        if categories is not None:
            return self.fileids(categories)
        else:
            return fileids
dataset/ETHPy150Open nltk/nltk/nltk/corpus/reader/plaintext.py/CategorizedPlaintextCorpusReader._resolve/operator `and` -> `or`