stylelint-bundle-worker.js
function concatNodes(pos, node, parent, options) {
  node.orig = node.val;
  var prev = this.prev();
  var last = utils.last(prev.nodes);
  var isEscaped = false;

  if (node.val.length > 1) {
    var a = node.val.charAt(0);
    var b = node.val.slice(-1);

    isEscaped = (a === '"' && b === '"')
      || (a === "'" && b === "'")
      || (a === '`' && b === '`');
  }

  if (isEscaped && options.unescape !== false) {
    node.val = node.val.slice(1, node.val.length - 1);
    node.escaped = true;
  }

  if (node.match) {
    var match = node.match[1];
    if (!match || match.indexOf('}') === -1) {
      match = node.match[0];
    }

    // replace each set with a single ","
    var val = match.replace(/\{/g, ',').replace(/\}/g, '');
    node.multiplier *= val.length;
    node.val = '';
  }

  var simpleText = last.type === 'text'
    && last.multiplier === 1
    && node.multiplier === 1
    && node.val;

  if (simpleText) {
    last.val += node.val;
    return;
  }

  prev.push(node);
}
function concatNodes(pos, node, parent, options) {
  node.orig = node.val;
  var prev = this.prev();
  var last = utils.last(prev.nodes);
  var isEscaped = false;

  if (node.val.length > 1) {
    var a = node.val.charAt(0);
    var b = node.val.slice(-1);

    isEscaped = (a === '"' && b === '"')
      || (a === "'" && b === "'")
      || (a === '`' && b === '`');
  }

  if (isEscaped && options.unescape !== false) {
    node.val = node.val.slice(1, node.val.length - 1);
    node.escaped = true;
  }

  if (node.match) {
    var match = node.match[1];
    if (!match || match.indexOf('}') === -1) {
      match = node.match[0];
    }

    // replace each set with a single ","
    var val = match.replace(/\{/g, ',').replace(/\}/g, '');
    node.multiplier *= val.length;
    node.val = '';
  }

  var simpleText = last.type === 'text'
    && last.multiplier === 1
    && node.multiplier === 1
    && node.val;

  if (simpleText) {
    last.val += node.val;
    return;
  }

  prev.push(node);
}
Combine text nodes, and calculate empty sets (`{,,}`)
@param {Function} `pos` Function to calculate node position
@param {Object} `node` AST node
@return {Object}