code: def _document_index_mask(self, feature: str, non_text: bool):
      term_idx_store = self.get_term_index_store(non_text=non_text)
      idx = term_idx_store.getidxstrict(feature.lower())
      mask = (
          (self.get_term_doc_mat(non_text=non_text)[:, idx] > 0)
          .todense()
          .A1
      )
      return mask
  
file_path: scattertext/scattertext/Corpus.py
imports: import numpy
  import pandas
  from numpy import nonzero
  from scattertext.TermDocMatrix import TermDocMatrix
label_desc: Use image node_id 6 for calling the Corpus obj's underlying member method code with example usage: obj._document_index_mask(feature, non_text) and returns: mask