code: function(){
                  /*
                   * media_query_list
                   *   : S* [media_query [ ',' S* media_query ]* ]?
                   *   ;
                   */
                  var tokenStream = this._tokenStream,
                      mediaList   = [];
  
                  this._readWhitespace();
                  if (tokenStream.peek() === Tokens.IDENT || tokenStream.peek() === Tokens.LPAREN){
                      mediaList.push(this._media_query());
                  }
  
                  while(tokenStream.match(Tokens.COMMA)){
                      this._readWhitespace();
                      mediaList.push(this._media_query());
                  }
                  return mediaList;
              }
docs: CSS3 Media Queries