```js
var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
var Node = function() {
this.keys = new Map();
this.end = false;
this.setEnd = function() {
this.end = true;
};
this.isEnd = function() {
return this.end;
};
};
var Trie = function() {
// change code below this line
// change code above this line
};
```
## Solution