declare
proc {BFS T}
   fun {TreeInsert Q T}
      if T\=leaf then {Insert Q T} else Q end
   end

   proc {BFSQueue Q1}
      if {IsEmpty Q1} then skip
      else X Q2 Key Val L R in
         Q2={Delete Q1 X}
         tree(Key Val L R)=X
         {Browse Key#Val}
         {BFSQueue {TreeInsert {TreeInsert Q2 L} R}}
      end
   end
in
   {BFSQueue {TreeInsert {NewQueue} T}}
end