'Do a forward pass through the network.
Args:
train: True if the forward pass is done during training, False during
evaluation.
step: Training step.'

def ForwardPropagate(self, train=False, step=0):

    losses = []
    for node in self.node_list:
        loss = self.ComputeUp(node, train, step, self.train_stop_steps)
        if loss:
            losses.append(loss)
    return losses
