For deme M, the population count was 5793 until a change 617.9355 generations ago, where it changed to 145, remaining steady thereafter.
time_units: generations
demes:
  - name: M
    start_time: .inf
    epochs:
      - start_size: 5793
        end_time: 617.9355
      - start_size: 145
        end_time: 0