code: def get_ext_param(self, ext_key, param_key):
          '''
          Get specific param in set of provided extension parameters.
          '''
          return self.extensions[ext_key][param_key] if self.extensions[ext_key]\
                  else Nonf get_ext_param(self, ext_key, param_key):
          '''
          Get specific param in set of provided extension parameters.
          '''
          return self.extensions[ext_key][param_key] if self.extensions[ext_key]\
                  else None
docs: Get specific param in set of provided extension parameters.