private ExpressionNode optimizeChildren(CompositeNode node, ContextIndex context) {
        List<ExpressionNode> children = node.children();
        List<ExpressionNode> optimizedChildren = new ArrayList<>(children.size());
        for (ExpressionNode child : children)
            optimizedChildren.add(optimize(child, context));
        return node.setChildren(optimizedChildren);
    }
Recognizes and optimizes tensor expressions.

@author lesters
searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/tensoroptimization/TensorOptimizer.java