function step_(x, alpha) {
	  if (alpha === void 0) {
	    alpha = 0.0;
	  }

	  var $x = convertToTensor(x, 'x', 'step');
	  var inputs = {
	    x: $x
	  };
	  var attrs = {
	    alpha: alpha
	  };
	  return ENGINE.runKernel(Step, inputs, attrs);
	}
Computes step of the input `tf.Tensor` element-wise: `x > 0 ? 1 : alpha * x`

```js
const x = tf.tensor1d([0, 2, -1, -3]);

x.step(.5).print();  // or tf.step(x, .5)
```
@param x The input tensor.
@param alpha The gradient when input is negative.

@doc {heading: 'Operations', subheading: 'Basic math'}