consider bridging behavior between user staring plan and ending logic
consider bridging behavior between user staring plan and ending logic

- [staring plan] -output-> ... -state-> [next starting plan (ending logic)]
- at the end of promise, find all subsequent promises created by `then`
- wrap user ending logic into `plan` format
- ask each subsequent Promise to attempt corresponding plan

chintown/simple-promise,chintown/simple-promise