code: function(input){
  
                  this._tokenStream = new TokenStream(input, Tokens);
  
                  //skip any leading white space
                  this._readWhitespace();
  
                  var result = this._selector();
  
                  //skip any trailing white space
                  this._readWhitespace();
  
                  //if there's anything more, then it's an invalid selector
                  this._verifyEnd();
  
                  //otherwise return result
                  return result;
              }
docs: Parses a single CSS selector (no comma)
  @param {String} input The text to parse as a CSS selector.
  @return {Selector} An object representing the selector.
  @throws parserlib.util.SyntaxError If an unexpected token is found.
  @method parseSelector