time_units: generations
defaults:
  epoch: {start_size: 1}
demes:
- {name: a}
- {name: b}
- {name: c}
- name: d
  epochs:
  - {start_size: 2}
- name: e
  epochs:
  - {end_time: 100}
  - {end_time: 50, end_size: 99}
  - {start_size: 3}
- name: f
  epochs:
  - {end_time: 100}
  - {end_time: 50, end_size: 99}
  - {start_size: 5, end_size: 99}
  defaults:
    epoch: {start_size: 4}