private static <T> Stream<TreeNode<Op<T>>>
	results(final TreeNode<Op<T>> node) {
		return node.stream()
			.filter(ConstRewriter::matches);
	}
Return the operation type this rewriter is working on.

@return the operation type this rewriter is working on
jenetics.prog/src/main/java/io/jenetics/prog/op/ConstRewriter.java