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procedure Op (M : in out Map) is
   C : Cursor;
   B : Boolean;
begin
   M.Insert (Key, E);
   M.Delete (Key);  -- by key
   M.Insert (Key, E, C, B);
   M.Delete (Position => C); -- by cursor
   M.Insert (Key, E);
   M.Exclude (Key); -- by key
end;