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if _n_ = 1 then do;
    declare hash lu(multidata:"no",hashexp:10);
    lu.definekey("key_var");
    lu.definedata("data_vars");
    lu.definedone();
end;
    
length d $20;
length k $20;

if _N_ = 1 then do;
   declare hash h();
   rc = h.defineKey('k');
   rc = h.defineData('d');
   rc = h.defineDone();
   call missing(k, d);
end;

data match;
   length k 8;
   length s 8;
   if _N_ = 1 then do;
      /* load SMALL data set into the hash object */
     declare hash h(dataset: "work.small");
      /* define SMALL data set variable K as key and S as value */
      h.defineKey('k');
      h.defineData('s');
      h.defineDone();
      /* avoid uninitialized variable notes */
      call missing(k, s);
   end;

/* use the SET statement to iterate over the LARGE data set using */
/* keys in the LARGE data set to match keys in the hash object */
set large;
rc = h.find();
if (rc = 0) then output;
run;