code: function appendStyle(style, doc) {
      if (!_.isString(style) || !doc) {
          console.log('invalid document or style string...', style, doc);
          return;
      }
      let docEl = (doc.getElementsByTagName('document')).item(0);
      let styleString = ['<style>', style, '</style>'].join('');
      let headTag = doc.getElementsByTagName('head');
  
      headTag = headTag && headTag.item(0);
      if (!headTag) {
          headTag = doc.createElement('head');
          docEl.insertBefore(headTag, docEl.firstChild);
      }
      headTag.innerHTML = styleString;
  }
docs: Adds style to a document.
  
  @todo Check for existing style tag within the head of the provided document and append if exists
  
  @private
  
  @param  {String} style Style string
  @param  {Document} doc   The document to add styles on