Output
```
Node {
  type: 'Program',
  start: 0,
  end: 15,
  body: [
    Node {
      type: 'VariableDeclaration',
      start: 0,
      end: 15,
      declarations: [Array],
      kind: 'let'
    }
  ],
  sourceType: 'script'
}
```
Output
```
Token { type: 'Keyword', value: 'let', start: 0, end: 3 },
Token { type: 'Identifier', value: 'foo', start: 4, end: 7 },
Token { type: 'Punctuator', value: '=', start: 8, end: 9 },
Token { type: 'String', value: '"bar"', start: 10, end: 15 }
```