For deme M, the population count was 4742 until a change 4364.0 generations ago, where it changed to 8847, remaining steady thereafter.
time_units: generations
demes:
  - name: M
    start_time: .inf
    epochs:
      - start_size: 4742
        end_time: 4364.0
      - start_size: 8847
        end_time: 0