style: simplify statements for readability

[hamirmahal]

Fixes #3142

Motivation

We can simplify some statements, like

(len, format!("http://{}/{}", authority, letter))

to improve code readability.

Solution

We replace lines like

(len, format!("http://{}/{}", authority, letter))

with

(len, format!("http://{authority}/{letter}"))

[hamirmahal]

This shouldn't cause any user-facing changes.

The goal of this pull request is to improve code readability and maintainability.

[kaffarell]

LGTM! Maybe reword the first commit message though – something like "examples: inline variables" would be better IMO.

[hamirmahal]

Sure! I'll do that right now.