Hi, do you know how to make a function returning a tower service builder?

[HaoliangXu]

https://github.com/SaadiSave/zero2prod/blob/main/src/startup.rs in this file, I feel that putting this trunk of code in Axum runner function is to noisy, makes it hard to read, so I like the idea of leaving the service builder in another function but making another function has its own problem, how to put the right return type on the function signature?