For the B deme, the population size remained at 3158 until 6747.1 generations ago, at which point a linear increase took place until 2347.6885 generations for size 5680. Afterward, the population saw an exponential change to 3891 by 1833.9. From 1833.9 generations ago to today, there's been a linear change from 3891 to 850.
time_units: generations
demes:
  - name: B
    start_time: .inf
    epochs:
      - start_size: 3158
        end_time: 6747.1
      - start_size: 3158
        end_size: 5680
        end_time: 2347.6885
        size_function: linear
      - start_size: 5680
        end_time: 1833.9
        end_size: 3891
        size_function: exponential
      - end_time: 0
        start_size: 3891
        end_size: 850
        size_function: linear