code: function differenceFromString (s, other) {
                      if(typeof other !== 'string' || typeof s !== 'string') return s;
                      var sarr = s.split(''), oarr = other.split('');
                      return libs.array.difference(sarr, oarr).join('');
                  }
docs: Returns all the characters found in one string but not the other.
  @param {String} s The string to operate on.
  @param {String} other The string to compute the difference against.
  @return {String} A difference string.