code: void hoistExterns(ImmutableList<CompilerInput> originalInputs) {
      boolean staleInputs = false;
  
      for (CompilerInput input : originalInputs) {
        if (hoistIfExtern(input)) {
          staleInputs = true;
        }
      }
      if (staleInputs) {
        repartitionInputs();
      }
    }
docs: Hoists inputs with the @externs annotation into the externs list.