Feedback from IMP-1

[npty]

Since the #76 PR is quite big, I think it is more appropriate to address them later to make it easier to review.

@StephenFluin

I have some minor comments and more improvements for later, but this PR can be merged as is. Looks great!

why don't we have a shared sleep method? (we seem to redefine it in many places
why did you refactor to use arrow functions?
Some typos in untouched code I'll fix once this PR lands
(later) Looks like a bunch of format / whitespace changes, can you make sure the whitespace settings are in prettier in our global package.json (or appropriate prettier config file) so we all autoformat the same?