code: def aggregate(self, other=None):
          '''collect the furthest failure from self and other.'''
          if not self.status:
              return self
          if not other:
              return self
          if not other.status:
              return other
          return Value(True, other.index, self.value + other.value, Nonef aggregate(self, other=None):
          '''collect the furthest failure from self and other.'''
          if not self.status:
              return self
          if not other:
              return self
          if not other.status:
              return other
          return Value(True, other.index, self.value + other.value, None)
docs: collect the furthest failure from self and other.