Swap Values

Write a function called swap that takes mutable borrows of two i32 values and swaps them. Print before and after to show the swap worked.

Expected output:

Before: a=10, b=20
After: a=20, b=10

Hints:

• Function signature: fn swap(a: &mut i32, b: &mut i32)
• Use a temporary variable: let temp = *a;
• Use *a and *b to read/write the values behind the references