code: def _get_documents(self):
          
          documents = self.tree.execute("$.documents")
          for doc in documents:
              sentences = {s['@id']: s['text'] for s in doc.get('sentences', [])}
              self.document_dict[doc['@id']] = {'sentences': sentences,
                                                'location': doc['location']}
docs: Populate sentences attribute with a dict keyed by document id.