docs: def MemberDiff(data1, set1_name, data2, set2_name):
      """Helper method to perform bidirectional set differences."""
      set1 = set(data1)
      set2 = set(data2)
      diffs = []
      msg = "Present in %s, missing in %s: %s"
      if set1 != set2:
        in_set1 = set1 - set2
        in_set2 = set2 - set1
        if in_set1:
          diffs.append(msg % (set1_name, set2_name, ",".join(in_set1)))
        if in_set2:
          diffs.append(msg % (set2_name, set1_name, ",".join(in_set2)))
      return diffs