def __init__(self, corpus, alternative_text_field=None):
        '''
        Parameters
        ----------
        corpus, Corpus: Corpus to extract documents and labels from
        alternative_text_field, str or None: if str, corpus must be parsed corpus
        '''
        # assert (isinstance(corpus, (Corpus, ParsedCorpus, CorpusDF, TermCategoryFrequencies))
        #		or (issubclass(type(corpus), (Corpus, ParsedCorpus, CorpusDF, TermCategoryFrequencies))))
        self._texts_to_display = None
        if alternative_text_field is not None:
            if not isinstance(corpus, ParsedCorpus):
                raise CorpusShouldBeParsedCorpusException(
                    'Corpus type needs to be ParsedCorpus to use the alternative text field.')
            self._texts_to_display = corpus.get_field(alternative_text_field)
        self._use_non_text_features = False
        self._use_terms_for_extra_features = False
        self._corpus = corpus

        Parameters
        ----------
        corpus, Corpus: Corpus to extract documents and labels from
        alternative_text_field, str or None: if str, corpus must be parsed corpus
        
scattertext/DocsAndLabelsFromCorpus.py