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