docstr: Returns
  -------
  PriorFactory
docstr_tok: ["Returns","--","--","--","-","PriorFactory"]
code: def drop_neutral_categories_from_corpus(self):
      """
      Returns
      -------
      PriorFactory
      """
      neutral_categories = self._get_neutral_categories()
      self.term_doc_mat = self.term_doc_mat.remove_categories(
          neutral_categories
      )
      self._reindex_priors()
      return self
  
imports: import pandas
  import numpy
  from scattertext.termranking import AbsoluteFrequencyRanker
  from scattertext.termsignificance.LogOddsRatioInformativeDirichletPiror import LogOddsRatioInformativeDirichletPrior
label_desc: Use image node_id 9 for calling the PriorFactory obj's underlying member method code with example usage: obj.drop_neutral_categories_from_corpus() and returns: self