code: def upper(self):
          '''Upper bound'''
          try:
              return self._model._limits_upper[self._reaction]
          except KeyError:
              return self._model._v_maf upper(self):
          '''Upper bound'''
          try:
              return self._model._limits_upper[self._reaction]
          except KeyError:
              return self._model._v_max
docs: Upper bound