P deme's population was steady at 7653 before it reduced to 3181 6904.5 generations ago, maintaining that number to the present.
time_units: generations
demes:
  - name: P
    start_time: .inf
    epochs:
      - start_size: 7653
        end_time: 6904.5
      - start_size: 3181
        end_time: 0