code: function getAtruler() {
    const type = NodeType.AtruleType;
    const token = tokens[pos];
    const line = token.ln;
    const column = token.col;
    const content = [].concat(
      getAtkeyword(),
      getTsets(),
      getAtrulers()
    );
  
    return newNode(type, content, line, column);
  }
docs: Gets node with an @-rule with ruleset.
  
  @return {!Node}