For deme Z, the population count was 6458 until a change 9859.73 generations ago, where it decreased to 4651, remaining steady thereafter.
time_units: generations
demes:
  - name: Z
    start_time: .inf
    epochs:
      - start_size: 6458
        end_time: 9859.73
      - start_size: 4651
        end_time: 0