code: def encrypt(self, document_id, content, account):
          
          return self._secret_store(account).encrypt_document(document_id, content)
docs: Encrypt string data using the DID as an secret store id,
          if secret store is enabled then return the result from secret store encryption
  
          None for no encryption performed
  
          :param document_id: hex str id of document to use for encryption session
          :param content: str to be encrypted
          :param account: Account instance encrypting this content
          :return: hex str encrypted content