'Record the fact that the given DocTest (`test`) generated `f`
failures out of `t` tried examples.'

def __record_outcome(self, test, f, t):

    (f2, t2) = self._name2ft.get(test.name, (0, 0))
    self._name2ft[test.name] = ((f + f2), (t + t2))
    self.failures += f
    self.tries += t
