An asynchronous reader-writer lock.| docs.rs
The 32-bit unsigned integer type.| doc.rust-lang.org
`Result` is a type that represents either success (`Ok`) or failure (`Err`).| doc.rust-lang.org
References, `&T` and `&mut T`.| doc.rust-lang.org
A thread-safe reference-counting pointer. ‘Arc’ stands for ‘Atomically Reference Counted’.| doc.rust-lang.org