presto-parser/src/main/java/io/prestosql/sql/ExpressionFormatter.java/Formatter/visitLambdaExpression
class Formatter:        @Override
        protected String visitLambdaExpression(LambdaExpression node, Void context)
        {
            StringBuilder builder = new StringBuilder();

            builder.append('(');
            Joiner.on(", ").appendTo(builder, node.getArguments());
            builder.append(") -> ");
            builder.append(process(node.getBody(), context));
            return builder.toString();
        }