code: function (first, last)
  	{
  		var count=0;
  		for (var i=first; i<=last; ++i) {
  			count+=this.isForbiddenCharacter(i)?1:0;
  		}
  		return count;
  	}
docs: Returns the number of forbidden characters in the interval (bounds inclusive)
  Characters : same as in isForbiddenCharacter()