def guided(model):
return backend.modify_model_backprop(model, '<STR_LIT>')<EOL>
Modifies backprop to only propagate positive gradients for positive activations.

    Args:
        model: The `keras.models.Model` instance whose gradient computation needs to be overridden.

    References:
        Details on guided back propagation can be found in paper: [String For Simplicity: The All Convolutional Net]
        (https://arxiv.org/pdf/1412.6806.pdf)