docs: function iconLookup(filename) {
    var ext = extname(filename);
  
    // try by extension
    if (icons[ext]) {
      return {
        className: 'icon-' + ext.substring(1),
        fileName: icons[ext]
      };
    }
  
    var mimetype = mime.lookup(ext);
  
    // default if no mime type
    if (mimetype === false) {
      return {
        className: 'icon-default',
        fileName: icons.default
      };
    }
  
    // try by mime type
    if (icons[mimetype]) {
      return {
        className: 'icon-' + mimetype.replace('/', '-'),
        fileName: icons[mimetype]
      };
    }
  
    var suffix = mimetype.split('+')[1];
  
    if (suffix && icons['+' + suffix]) {
      return {
        className: 'icon-' + suffix,
        fileName: icons['+' + suffix]
      };
    }
  
    var type = mimetype.split('/')[0];
  
    // try by type only
    if (icons[type]) {
      return {
        className: 'icon-' + type,
        fileName: icons[type]
      };
    }
  
    return {
      className: 'icon-default',
      fileName: icons.default
    };
  }