Penrose tiling with Lindenmayer Systems

var level = 6;
var axiom = '[7]++[7]++[7]++[7]++[7]';
var rules = {
    '6' : '81++91----71[-81----61]++',
    '7' : '+81--91[---61--71]+',
    '8' : '-61++71[+++81++91]-',
    '9' : '--81++++61[+91++++71]--71',
    '1' : '',
    '+' : '+',
    '-' : '-',
    '[' : '[',
    ']' : ']'
  };
var symbols = { 
                '1':'F',
                '6':' ',
                '7':' ',
                '8':' ',
                '9':' ',
                '+':'+',
                '-':'-',
                '[':'[',
                ']':']'
               };
var angle = 36.0;
var len = 100/(level);
t.setProperty({fillcolor:'#ff99cc'});