function iteratorFromFunction(func) {
	  return new FunctionCallIterator(func);
	}
Create a `LazyIterator` from a function.

```js
let i = -1;
const func = () =>
   ++i < 5 ? {value: i, done: false} : {value: null, done: true};
const iter = tf.data.iteratorFromFunction(func);
await iter.forEachAsync(e => console.log(e));
```

@param func A function that produces data on each call.