def value(self, ob, *args, **kwargs):
return self._evaluate(self.vf, ob, *args, **kwargs)<EOL>
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