function random_color(format){ 
  var rint = Math.round(0xffffff * Math.random()); 
  switch(format) {  
    case 'hex':   return ('#0' + rint.toString(16)).replace(/^#0([0-9a-f]{6})$/i, '#$1');  break;    
    case 'rgb':   return 'rgb(' + (rint >> 16) + ',' + (rint >> 8 & 255) + ',' + (rint & 255) + ')';  break;    
    default:   
     return rint;  
     break; 
  }
}

function removeElement(element) {
   return element.parentNode.removeChild(element);
}

Array.prototype.has=function(v){
  for (i=0;i<this.length;i++){
	if (this[i]==v) return true;
  }
  return false;
}


function iterator(base) {
     var idx = base;
     return function () {
          return idx++;
     }
}