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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def transcripts(self, contig=None, strand=None):
 """ Construct Transcript object for every transcript entry in the database. Optionally restrict to a particular chromosome using the `contig` argument. """

        transcript_ids = self.transcript_ids(contig=contig, strand=strand)
        return [
            self.transcript_by_id(transcript_id)
            for transcript_id in transcript_ids
        ]