Add a helper to filter in/out examples that do not fit a `Pydantic` validator

It should probably be a .pipe()-helper.

[koaning]

Come to think of it, I suppose impute could be easily implemented via;

def impute(self, **kwargs):
    return self.map(lambda d: {**kwargs, **d})

[koaning]

Your example is a nice one but I suppose in this example you could’ve also used map.

base_pokemon = {'name': 'Charmander', 'total': 309, 'hp': 39, 'attack': 52}

clump.map(lambda d: {**base_pokemon, **d)}

An impute method wouldn’t hurt though.