Until 50.6186 generations ago, the population of deme S was 9723. At that point, it changed to 2268, where it has stayed up to now.
time_units: generations
demes:
  - name: S
    start_time: .inf
    epochs:
      - start_size: 9723
        end_time: 50.6186
      - start_size: 2268
        end_time: 0