code: def record_calculation_end(self, variable_name, period, result, **parameters):
          
          key = self._get_key(variable_name, period, **parameters)
          expected_key = self.stack.pop()
  
          if not key == expected_key:
              raise ValueError(
                  "Something went wrong with the simulation tracer: result of '{0}' was expected, got results for '{1}' instead. This does not make sense as the last variable we started computing was '{0}'."
                  .format(expected_key, key)
                  )
          self.trace[key]['value'] = result
docs: Record that OpenFisca finished computing a variable.
  
              :param str variable_name: Name of the variable starting to be computed
              :param Period period: Period for which the variable is being computed
              :param numpy.ndarray result: Result of the computation
              :param list parameters: Parameter with which the variable is being computed