Boilerplate to make doctests pass

[Hoverbear]

#189 with feedback applied.

Closes #70.

[nrc]

lgtm

[Hoverbear]

@hicqu PTAL

[CLAassistant]

Thank you for your submission, we really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
2 out of 3 committers have signed the CLA.

✅ hicqu
✅ Hoverbear
❌ KeeganMyers
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[Hoverbear]

Seems we must close this because we cannot merge it due to our CLA. If someone wants to redo this work we can merge it.