code: public Stream<TreeMatchResult<V>> results() {
  		return _tree.stream()
  			.flatMap((Tree<V, ?> tree) -> _pattern.match(tree, _equals)
  				.map(Stream::of)
  				.orElseGet(Stream::empty));
  	}
docs: Return all matching <em>sub</em>-trees.
  
  @return all matching sub-trees
  @throws NullPointerException if the given predicate is {@code null}