Originally, deme P had a population size of 123, which changed to 7361 around 3828.75 generations ago and has not changed since.
time_units: generations
demes:
  - name: P
    start_time: .inf
    epochs:
      - start_size: 123
        end_time: 3828.75
      - start_size: 7361
        end_time: 0