presto-parser/src/main/java/io/prestosql/sql/ExpressionFormatter.java/ExpressionFormatter/visitCoalesceExpression
class ExpressionFormatter:        @Override
        protected String visitCoalesceExpression(CoalesceExpression node, Void context)
        {
            return "COALESCE(" + joinExpressions(node.getOperands()) + ")";
        }