'Constructs the theano expression that samples from the output layer.
:type state_below: tensor or layer
:param state_below: The theano expression (or groundhog layer)
representing the input of the cost layer
:type temp: float or tensor scalar
:param temp: scalar representing the temperature that should be used
when sampling from the output distribution
:type use_noise: bool
:param use_noise: flag. If true, noise is used when computing the
output of the model'

def compute_sample(self, state_below, temp=1, use_noise=False):

    raise NotImplemented
