code: def get_bel_stmts(self, filter=False):
          
          if self.basename is not None:
              bel_stmt_path = '%s_bel_stmts.pkl' % self.basename
          # Check for cached BEL stmt file
          if self.basename is not None and os.path.isfile(bel_stmt_path):
              logger.info("Loading BEL statements from %s" % bel_stmt_path)
              with open(bel_stmt_path, 'rb') as f:
                  bel_statements = pickle.load(f)
          # No cache, so perform the queries
          else:
              bel_proc = bel.process_pybel_neighborhood(self.gene_list,
                  network_file=self.bel_corpus)
              bel_statements = bel_proc.statements
              # Save to pickle file if we're caching
              if self.basename is not None:
                  with open(bel_stmt_path, 'wb') as f:
                      pickle.dump(bel_statements, f)
          # Optionally filter out statements not involving only our gene set
          if filter:
              if len(self.gene_list) > 1:
                  bel_statements = ac.filter_gene_list(bel_statements,
                                                       self.gene_list, 'all')
          return bel_statements
docs: Get relevant statements from the BEL large corpus.
  
          Performs a series of neighborhood queries and then takes the union of
          all the statements. Because the query process can take a long time for
          large gene lists, the resulting list of statements are cached in a
          pickle file with the filename `<basename>_bel_stmts.pkl`.  If the
          pickle file is present, it is used by default; if not present, the
          queries are performed and the results are cached.
  
          Parameters
          ----------
          filter : bool
              If True, includes only those statements that exclusively mention
              genes in :py:attr:`gene_list`. Default is False. Note that the
              full (unfiltered) set of statements are cached.
  
          Returns
          -------
          list of :py:class:`indra.statements.Statement`
              List of INDRA statements extracted from the BEL large corpus.