* Closes 11 by mharrisb1 in https://github.com/mharrisb1/daglib/pull/16
* Release/v.0.2.1 by mharrisb1 in https://github.com/mharrisb1/daglib/pull/17
* Add documentation example for how to correctly handle `wait_for` by mharrisb1 in https://github.com/mharrisb1/daglib/pull/20
* Move exceptions to their own module by mharrisb1 in https://github.com/mharrisb1/daglib/pull/22