Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Literal UInt64_1
    TablesInSelectQuery (children 3)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier v0
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       Subquery (alias y) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 1)
           ExpressionList (children 1)
            Literal UInt64_1
      TableJoin
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       Subquery (alias x) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 1)
           ExpressionList (children 1)
            Literal UInt64_1 (alias x)
      TableJoin
    Function equals (children 1)
     ExpressionList (children 2)
      Identifier x.x
      Literal UInt64_1
