code: def _transform_call_params(self, params):
          
          rez = {}
          for k, v in params.items():
              if isinstance(v, dict):
                  v = self._transform_call_params(v)
                  k_final = k
              else:
                  # k = modifier1@modifier2@...modifierN@k_final
                  k_split = k.split("@")
                  k_final = k_split[-1]
                  k_mods  = k_split[:-1]
                  for m in k_mods:
                      if (m == "file"):
                          with open(v, 'rb') as f:
                              v = f.read()
                      elif (m == "b64encode"):
                          v = base64.b64encode(v)
                      elif (m == "b64decode"):
                          v = base64.b64decode(v)
                      else:
                          raise Exception("Unknown modifier ('%s') in call parameters. Possible modifiers: file, b64encode, b64decode"%m)
              rez[k_final] = v
          return rez
docs: possible modifiers: file, b64encode, b64decode
          format:             modifier1@modifier2@...modifierN@k_final