SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function mapUpdate (children 1)
     ExpressionList (children 2)
      Function map (children 1)
       ExpressionList (children 4)
        Literal \'k1\'
        Literal UInt64_1
        Literal \'k2\'
        Literal UInt64_2
      Function materialize (children 1)
       ExpressionList (children 1)
        Function map (children 1)
         ExpressionList (children 4)
          Literal \'k3\'
          Literal UInt64_33
          Literal \'k4\'
          Literal UInt64_44
