The number of individuals in deme O remained at 1438 until 8039.03 generations ago, at which time it changed to a new stable size of 1455.
time_units: generations
demes:
  - name: O
    start_time: .inf
    epochs:
      - start_size: 1438
        end_time: 8039.03
      - start_size: 1455
        end_time: 0