code: def context_chunks(self, context):
          
  
          chunks = []
          papers = []
          for paper, feature in self.features.iteritems():
              if context in feature.contexts:
                  new_chunks = feature.context_chunks(context)
              else:
                  new_chunks = list(feature)
              indices = range(len(chunks), len(chunks) + len(new_chunks))
              papers.append((paper, indices))
              chunks += new_chunks
          return papers, chunks
docs: Retrieves all tokens, divided into the chunks in context ``context``.
  
          If ``context`` is not found in a feature, then the feature will be
          treated as a single chunk.
  
          Parameters
          ----------
          context : str
              Context name.
  
          Returns
          -------
          papers : list
              2-tuples of (paper ID, chunk indices).
          chunks : list
              Each item in ``chunks`` is a list of tokens.