code: def encrypt(self, message):
          
          if not message:
              return None
  
          nonce = str(random.getrandbits(64))
          try:
              memo_wif = self.blockchain.wallet.getPrivateKeyForPublicKey(
                  self.from_account["options"]["memo_key"]
              )
          except KeyNotFound:
              # if all fails, raise exception
              raise MissingKeyError(
                  "Memo private key {} for {} could not be found".format(
                      self.from_account["options"]["memo_key"], self.from_account["name"]
                  )
              )
          if not memo_wif:
              raise MissingKeyError(
                  "Memo key for %s missing!" % self.from_account["name"]
              )
  
          if not hasattr(self, "chain_prefix"):
              self.chain_prefix = self.blockchain.prefix
  
          enc = memo.encode_memo(
              self.privatekey_class(memo_wif),
              self.publickey_class(
                  self.to_account["options"]["memo_key"], prefix=self.chain_prefix
              ),
              nonce,
              message,
          )
  
          return {
              "message": enc,
              "nonce": nonce,
              "from": self.from_account["options"]["memo_key"],
              "to": self.to_account["options"]["memo_key"],
          }
docs: Encrypt a memo
  
              :param str message: clear text memo message
              :returns: encrypted message
              :rtype: str