anchor.diff:  
   // check if the string is a float
   bool isFloat(String str) {
  -  return float.hasMatch(str);
  +  return _float.hasMatch(str);
   }
   
   
  
positive.code: RegExp alphanumeric = new RegExp(r'^[a-zA-Z0-9]+$');
  RegExp numeric = new RegExp(r'^-?[0-9]+$');
  RegExp _int = new RegExp(r'^(?:-?(?:0|[1-9][0-9]*))$');
  RegExp float = new RegExp(r'^(?:-?(?:[0-9]+))?(?:\.[0-9]*)?(?:[eE][\+\-]?(?:[0-9]+))?$');
  RegExp hexadecimal = new RegExp(r'^[0-9a-fA-F]+$');
  RegExp hexcolor = new RegExp(r'^#?([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$');
  
  
negative.code: bool isUppercase(String str) {
    return str == str.toUpperCase();
  }
  
  
  // check if the string is a number that's divisible by another
  bool isDivisibleBy(String str, n) {
    return double.parse(str) % int.parse(n) == 0;
  }
  