code: def value(self, ob, *args, **kwargs):
          
          return self._evaluate(self.vf, ob, *args, **kwargs)
docs: Compute value estimate(s) given the observation(s)
  
          Parameters:
          ----------
  
          observation     observation data (either single or a batch)
  
          **extra_feed    additional data such as state or mask (names of the arguments should match the ones in constructor, see __init__)
  
          Returns:
          -------
          value estimate