Until a shift occurred 9228.6 generations ago, deme M's population was consistently 7331. Since then, it changed to 463, a number that has remained unchanged to the current time.
time_units: generations
demes:
  - name: M
    start_time: .inf
    epochs:
      - start_size: 7331
        end_time: 9228.6
      - start_size: 463
        end_time: 0