function Container() {
        _classCallCheck(this, Container);

        return _possibleConstructorReturn(this, _Node.apply(this, arguments));
    }
The {@link Root}, {@link AtRule}, and {@link Rule} container nodes
inherit some common methods to help work with their children.

Note that all containers can store any content. If you write a rule inside
a rule, PostCSS will parse it.

@extends Node
@abstract