Until 2715.73 generations ago, the population of deme U was 7906. At that point, it changed to 1701, where it has stayed up to now.
time_units: generations
demes:
  - name: U
    start_time: .inf
    epochs:
      - start_size: 7906
        end_time: 2715.73
      - start_size: 1701
        end_time: 0