function Rule(defaults) {
        _classCallCheck(this, Rule);

        var _this = _possibleConstructorReturn(this, _Container.call(this, defaults));

        _this.type = 'rule';
        if (!_this.nodes) _this.nodes = [];
        return _this;
    }
Represents a CSS rule: a selector followed by a declaration block.

@extends Container

@example
const root = postcss.parse('a{}');
const rule = root.first;
rule.type       //=> 'rule'
rule.toString() //=> 'a{}'