Until 799.413 generations ago, the population of deme Q was 1339. At that point, it changed to 216, where it has stayed up to now.
time_units: generations
demes:
  - name: Q
    start_time: .inf
    epochs:
      - start_size: 1339
        end_time: 799.413
      - start_size: 216
        end_time: 0