code: public UnicodeSet complementAll(UnicodeSet c) {
          checkFrozen();
          xor(c.list, c.len, 0);
          SortedSetRelation.doOperation(strings, SortedSetRelation.COMPLEMENTALL, c.strings);
          return this;
      }
docs: Complements in this set all elements contained in the specified
  set.  Any character in the other set will be removed if it is
  in this set, or will be added if it is not in this set.
  
  @param c set that defines which elements will be complemented from
  this set.