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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 _to_upper(self):
 """Convert sequences to upper case."""

        self.exon_seq = self.exon_seq.upper()
        self.three_prime_seq = [s.upper() for s in self.three_prime_seq]
        self.five_prime_seq = [s.upper() for s in self.five_prime_seq]