Notas Hellout

The first draft implementation is twice slower than repeated `push`es (after forcing the entire tree by calling `.measure()`). Not forcing the tree makes the operation run twice faster than repeated...

> Plan moved [up](https://github.com/functional-data-structure/finger-tree/issues/120#issue-787522112).

For **ii**: If implementing the `default` branch generically we could use `nodes` to create any `Tree` from scratch (see #108).

iii. is actually Exercise 3 (page 9) in Hinze and Paterson (see README for link).

@niklas-e Another way to implement this would be to proxy all state changes. This would not work well with independent code fiddling with the storage, but if you have control...

@grazzolini Can you have a look?

Maybe adding an error message in `display_fingerprints` in case keys are missing at that point would be beneficial.

> LGTM so far. Could you add the error message and remove the draft flag? Just added 294b419.

@iiroj Ah. When I say changes I mean changes introduced by the configuration of `lint-staged` itself: some linters can be configured to autofix lint, and `lint-staged` stages those additional changes....

Was struggling with a similar issue. Essentially, the following does not work: ```ignore * !a/b/** ``` You need ```ignore * !a/ !a/b/** ```