presto-main/src/main/java/io/prestosql/sql/relational/optimizer/ExpressionOptimizer.java/Visitor/visitLambda
class Visitor:        @Override
        public RowExpression visitLambda(LambdaDefinitionExpression lambda, Void context)
        {
            return new LambdaDefinitionExpression(lambda.getArgumentTypes(), lambda.getArguments(), lambda.getBody().accept(this, context));
        }