M deme's population was steady at 4997 before it changed to 9453 7779.326 generations ago, maintaining that number to the present.
time_units: generations
demes:
  - name: M
    start_time: .inf
    epochs:
      - start_size: 4997
        end_time: 7779.326
      - start_size: 9453
        end_time: 0