Explain EXPLAIN QUERY TREE (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 2)
     Function grouping (children 1)
      ExpressionList (children 1)
       Identifier id
     Function grouping (children 1)
      ExpressionList (children 1)
       Identifier value
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test_table
    ExpressionList (children 2)
     Identifier id
     Identifier value