function dropout$2(args) {
	  return new Dropout(args);
	}
Applies
[dropout](http://www.cs.toronto.edu/~rsalakhu/papers/srivastava14a.pdf) to
the input.

Dropout consists in randomly setting a fraction `rate` of input units to 0 at
each update during training time, which helps prevent overfitting.

@doc {heading: 'Layers', subheading: 'Basic', namespace: 'layers'}