The number of individuals in deme X remained at 6140 until 3234.0252 generations ago, at which time it changed to a new stable size of 1239.
time_units: generations
demes:
  - name: X
    start_time: .inf
    epochs:
      - start_size: 6140
        end_time: 3234.0252
      - start_size: 1239
        end_time: 0