For deme U, the population count was 8537 until a change 7032.1808 generations ago, where it reduced to 7260, remaining steady thereafter.
time_units: generations
demes:
  - name: U
    start_time: .inf
    epochs:
      - start_size: 8537
        end_time: 7032.1808
      - start_size: 7260
        end_time: 0