function parse(html, doc) {
  if ('string' != typeof html) throw new TypeError('String expected');

  // default to the global `document` object
  if (!doc) doc = document;

  // tag name
  var m = /<([\w:]+)/.exec(html);
  if (!m) return doc.createTextNode(html);

  html = html.replace(/^\s+|\s+$/g, ''); // Remove leading/trailing whitespace

  var tag = m[1];

  // body support
  if (tag == 'body') {
    var el = doc.createElement('html');
    el.innerHTML = html;
    return el.removeChild(el.lastChild);
  }

  // wrap map
  var wrap = map[tag] || map._default;
  var depth = wrap[0];
  var prefix = wrap[1];
  var suffix = wrap[2];
  var el = doc.createElement('div');
  el.innerHTML = prefix + html + suffix;
  while (depth--) el = el.lastChild;

  // one element
  if (el.firstChild == el.lastChild) {
    return el.removeChild(el.firstChild);
  }

  // several elements
  var fragment = doc.createDocumentFragment();
  while (el.firstChild) {
    fragment.appendChild(el.removeChild(el.firstChild));
  }

  return fragment;
}
Parse `html` and return a DOM Node instance, which could be a TextNode,
HTML DOM Node of some kind (<div> for example), or a DocumentFragment
instance, depending on the contents of the `html` string.

@param {String} html - HTML string to "domify"
@param {Document} doc - The `document` instance to create the Node for
@return {DOMNode} the TextNode, DOM Node, or DocumentFragment instance
@api private