code: def process(self, sessionRecord, message):
          
  
          messageVersion = message.getMessageVersion()
          theirIdentityKey = message.getIdentityKey()
  
          unsignedPreKeyId = None
  
          if not self.identityKeyStore.isTrustedIdentity(self.recipientId, theirIdentityKey):
              raise UntrustedIdentityException(self.recipientId, theirIdentityKey)
  
          if messageVersion == 2:
              unsignedPreKeyId = self.processV2(sessionRecord, message)
          elif messageVersion == 3:
              unsignedPreKeyId = self.processV3(sessionRecord, message)
          else:
              raise AssertionError("Unkown version %s" % messageVersion)
  
          self.identityKeyStore.saveIdentity(self.recipientId, theirIdentityKey)
  
          return unsignedPreKeyId
docs: :param sessionRecord:
          :param message:
          :type message: PreKeyWhisperMessage