use(plugin) {
    plugin.call(this, this);
    return this;
  }
Use an enquirer plugin.

```js
const Enquirer = require('enquirer');
const enquirer = new Enquirer();
const plugin = enquirer => {
  // do stuff to enquire instance
};
enquirer.use(plugin);
```
@name use()
@param {Function} `plugin` Plugin function that takes an instance of Enquirer.
@return {Object} Returns the Enquirer instance.
@api public