I wouldn't take this as representative of normal Rust code. This is standard nom which I would categorize very much as a DSL of sorts for creating parser combinators. In order to understand this code you really have to understand the fundamentals of nom as the reason it is so powerful is because there is a bit of magic going on here.

Also, I knew this piece of code looked familiar. For those that wanted to see this code with whitespace, https://github.com/GGist/bip-rs/blob/master/bip_utracker/src....