code: def fulfill(self):
          
          is_fulfilled, result = self._check_fulfilled()
  
          if is_fulfilled:
              return result
          else:
              raise BrokenPromise(self)
docs: Evaluate the promise and return the result.
  
          Returns:
               The result of the `Promise` (second return value from the `check_func`)
  
          Raises:
              BrokenPromise: the `Promise` was not satisfied within the time or attempt limits.