1. Run an Adam optimizer with the objective of minimizing the cost for a given learning_rate:

optimizer = tf$train$AdamOptimizer(learning_rate=1e-4)$minimize(cost)

2. Extract the number of correct_predictions and calculate the mean percentage accuracy:

correct_prediction = tf$equal(y_pred_cls, y_true_cls)
accuracy = tf$reduce_mean(tf$cast(correct_prediction, tf$float32))