Until 2130.27 generations ago, the population of deme W was 2543. At that point, it changed to 4354, where it has stayed up to now.
time_units: generations
demes:
  - name: W
    start_time: .inf
    epochs:
      - start_size: 2543
        end_time: 2130.27
      - start_size: 4354
        end_time: 0