Explain EXPLAIN (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Function plus (children 1)
      ExpressionList (children 2)
       Identifier x
       Identifier y
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier morton
    Function equals (children 1)
     ExpressionList (children 2)
      Function plus (children 1)
       ExpressionList (children 2)
        Identifier x
        Literal UInt64_1
      Literal UInt64_101
