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