Refutability in Rust Pattern Matching

# Introduction

Welcome to **Refutability: Whether a Pattern Might Fail to Match**. This lab is a part of the [Rust Book](https://doc.rust-lang.org/book/). You can practice your Rust skills in LabEx.

In this lab, we will learn about the concept of refutability in patterns and how it affects the matching process in Rust, including the distinction between refutable and irrefutable patterns and how to use them correctly in different constructs such as `let` statements and `if let` expressions.