Explain EXPLAIN QUERY TREE (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Function lambda (alias lambda) (children 1)
      ExpressionList (children 2)
       Function tuple (children 1)
        ExpressionList (children 1)
         Identifier x
       Function plus (children 1)
        ExpressionList (children 2)
         Identifier x
         Literal UInt64_1
    ExpressionList (children 1)
     Function lambda (children 1)
      ExpressionList (children 1)
       Identifier id
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test_table