public static <T> Extractor<T> value(final T value) {
    return new Extractor<T>() {
      @Override
      public T get(Context<Object> context) {
        return value;
      }

      @Override
      public String toString() {
        return Extractions.class.getSimpleName() + ".value(" + value + ")";
      }
    };
  }
Parboiled extraction for the sake of AST building.
trees/src/org/immutables/trees/ast/Extractions.java