title: tensorflow: what's the difference between tf.nn.dropout and tf.layers.dropout
body: <p>I'm quite confused about whether to use tf.nn.dropout or tf.layers.dropout.</p>
  
  <p>many MNIST CNN examples seems to use tf.nn.droput, with keep_prop as one of params. </p>
  
  <p>but how is it different with tf.layers.dropout? is the "rate" params in tf.layers.dropout similar to tf.nn.dropout?</p>
  
  <p>Or generally speaking, is the difference between tf.nn.dropout and tf.layers.dropout applies to all other similar situations, like similar functions in tf.nn and tf.layers. </p>