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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 wif(self, is_compressed=None):
 """ Return the WIF representation of this key, if available. """

        secret_exponent = self.secret_exponent()
        if secret_exponent is None:
            return None
        if is_compressed is None:
            is_compressed = self.is_compressed()
        blob = to_bytes_32(secret_exponent)
        if is_compressed:
            blob += b'\01'
        return self._network.wif_for_blob(blob)