code: function intersectString (s, other) {
                      if(typeof other !== 'string' || typeof s !== 'string') return s;
                      var sarr = s.split(''), oarr = other.split('');
                      return libs.array.intersect(sarr, oarr).join('');
                  }
docs: Returns only the characters common to both strings
  @param {String} s The string to operate on.
  @param {String} other The string to compute the intersection against.
  @return {String} The intersection between the two strings.