Up until 1035.0 generations ago, the count of B deme was 3556. Following that period, it reduced to 1577, where it has persisted until now.
time_units: generations
demes:
  - name: B
    start_time: .inf
    epochs:
      - start_size: 3556
        end_time: 1035.0
      - start_size: 1577
        end_time: 0