code: def setUnacknowledgedPreKeyMessage(self, preKeyId, signedPreKeyId, baseKey):
          
          self.sessionStructure.pendingPreKey.signedPreKeyId = signedPreKeyId
          self.sessionStructure.pendingPreKey.baseKey = baseKey.serialize()
  
          if preKeyId is not None:
              self.sessionStructure.pendingPreKey.preKeyId = preKeyId
docs: :type preKeyId: int
          :type signedPreKeyId: int
          :type baseKey: ECPublicKey