Go Walkthrough: fmt
Ben Johnson

Real use case for implementing custom Formatter, would be a human friendly byte counter type, which would dynamically adjust its value and unit name. For example:

given 12345 bytes would display as 12.06 KiB
given 12345678 bytes would display as 11.77 MiB

Here is the real [code](https://github.com/vbauerster/mpb/blob/master/decor/counters.go).

Also one should not assume, that wid will be always zero in the following call:

wid, _ := f.Width()

if the second value ok is false, then wid could be any value of typeint . So I recommend always to check the ok value.