[erlang-questions] Why we need to use make_ref in pmap ?

[lang qiu]

Hi all,

Why we need to use make_ref/0 in pmap ? To be exact, why we need to use
make_ref in the gather/2,

gather([Pid|T], Ref) ->
  receive
  {Pid, Ref, Ret} -> [Ret|gather(T, Ref)]
end;

Can't we just use gather/1,

gather([Pid|T]) ->
  receive
  {Pid, Ret} -> [Ret|gather(T)]
end;

Thanks !

Qiulang
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