The population of deme C held at 3162 until 1979.0 generations back, when it changed reaching 3952, which has been constant since then.
time_units: generations
demes:
  - name: C
    start_time: .inf
    epochs:
      - start_size: 3162
        end_time: 1979.0
      - start_size: 3952
        end_time: 0