code: def transcripts(self, contig=None, strand=None):
          
          transcript_ids = self.transcript_ids(contig=contig, strand=strand)
          return [
              self.transcript_by_id(transcript_id)
              for transcript_id in transcript_ids
          ]
docs: Construct Transcript object for every transcript entry in
          the database. Optionally restrict to a particular
          chromosome using the `contig` argument.