SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Identifier a2
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab1
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier tab2
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Function plus (children 1)
         ExpressionList (children 2)
          Identifier b1
          Literal UInt64_1
        Function plus (children 1)
         ExpressionList (children 2)
          Identifier a2
          Literal UInt64_1