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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 utr5(self):
 """ return the 5' UTR if appropriate """

        if not self.is_coding or len(self.exons) < 2: return (None, None)
        if self.strand == "+":
            s, e = (self.txStart, self.cdsStart)
        else:
            s, e = (self.cdsEnd, self.txEnd)
        if s == e: return (None, None)
        return s, e