The population of deme C held at 6021 until 6972.0 generations back, when it increased reaching 7503, which has been constant since then.
time_units: generations
demes:
  - name: C
    start_time: .inf
    epochs:
      - start_size: 6021
        end_time: 6972.0
      - start_size: 7503
        end_time: 0