Return `Hooks` that store activations of all `modules` in `self.stored`

def hook_outputs(modules:Collection[nn.Module], detach:bool=True, grad:bool=False)->Hooks:
    "Return `Hooks` that store activations of all `modules` in `self.stored`"
    return Hooks(modules, _hook_inner, detach=detach, is_forward=not grad)