code: function createItemContent(cfg, item) {
    var data = item.children || cfg.data;
    var frag = document.createDocumentFragment();
    var label = _.el('span');
    var iconPrepend = _.el('i');
    var iconAppend = _.el('i');
    var prependClasses = ['fa'];
    var appendClasses = ['fa'];
  
    // prepended icon
    if (data) {
      prependClasses.push('fa-folder');
    } else if (item.type === 'github-url') {
      prependClasses.push('fa-github');
    } else {
      prependClasses.push('fa-file-o');
    }
    _.addClass(iconPrepend, prependClasses);
  
    // text label
    _.append(label, [iconPrepend, _.text(item.label)]);
    frag.appendChild(label);
  
    // appended icon
    if (data) {
      appendClasses.push('fa-caret-right');
    } else if ('url' in item) {
      appendClasses.push('fa-external-link');
    }
    _.addClass(iconAppend, appendClasses);
    frag.appendChild(iconAppend);
  
    return frag;
  }
docs: how each item in a column should be rendered