Originally, deme B had a population size of 3014, which changed to 9633 around 4719.8408 generations ago and has not changed since.
time_units: generations
demes:
  - name: B
    start_time: .inf
    epochs:
      - start_size: 3014
        end_time: 4719.8408
      - start_size: 9633
        end_time: 0