The number of individuals in deme S remained at 2270 until 1255.0 generations ago, at which time it increased to a new stable size of 6425.
time_units: generations
demes:
  - name: S
    start_time: .inf
    epochs:
      - start_size: 2270
        end_time: 1255.0
      - start_size: 6425
        end_time: 0