protected T aggregateResult(T aggregate, T nextResult) {
		return nextResult;
	}
Aggregates the results of visiting multiple children of a node. After
either all children are visited or {@link #shouldVisitNextChild} returns
{@code false}, the aggregate value is returned as the result of
{@link #visitChildren}.

<p>The default implementation returns {@code nextResult}, meaning
{@link #visitChildren} will return the result of the last child visited
(or return the initial value if the node has no children).</p>

@param aggregate The previous aggregate value. In the default
implementation, the aggregate value is initialized to
{@link #defaultResult}, which is passed as the {@code aggregate} argument
to this method after the first child node is visited.
@param nextResult The result of the immediately preceeding call to visit
a child node.

@return The updated aggregate result.
runtime/Java/src/org/antlr/v4/runtime/tree/AbstractParseTreeVisitor.java