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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 add_transcription(self, gene: Gene, rna: Union[Rna, MicroRna]) -> str: """Add a transcription relation from a gene to an RNA or miRNA node. :param gene: A gene node :param rna: An RNA or microRNA node """

        return self.add_unqualified_edge(gene, rna, TRANSCRIBED_TO)