docs: public static MutableChar fromExternal(final Supplier<Character> s, final Consumer<Character> c) {
          return new MutableChar() {
              @Override
              public char getAsChar() {
                  return s.get();
              }
  
              @Override
              public Character get() {
                  return getAsChar();
              }
  
              @Override
              public MutableChar set(final char value) {
                  c.accept(value);
                  return this;
              }
          };
      }