Are you referring to "sha1 hash is not valid".into()? This is a "not very useful name" because it is a very generic (and core) trait. https://doc.rust-lang.org

Are you referring to "sha1 hash is not valid".into()? This is a "not very useful name" because it is a very generic (and core) trait. https://doc.rust-lang.org/std/convert/trait.Into.html https://doc.rust-lang.org/std/convert/trait.Into.html This is the standard interface for converting anything into anything. The way this is often used relies on type-inference. In this case it is being used as `return Err("sha1 hash is not valid".into())` inside a function that returns `Result<(), Box<dyn Error>>`. This means that the expression is inferred to evaluate to a `Box<dyn Error>`. Luckily there is an implementation of the Into trait for &str to that type (https://doc.rust-lang.org/std/convert/trait.From.html#impl-From%3C%26str%3E-for-Box%3Cdyn%20Error%20+%20Send%20+%20Sync%20+%20%27a%3E https://doc.rust-lang.org/std/convert/trait.From.html#impl-F...). So `.into()` just does the right thing. This is a less common use case but the most common one I see is: let s: String = "foobar".into() Which converts a &'static str to a String.