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fn add_and_print(x: &mut i32) {
*x += 1;
println!("The value of x in add_and_print is {}.", x);
// mutable reference to x is dropped
}
fn main() {
let mut x = 1; // Declare a mutable variable x
add_and_print(&mut x); // Modify x in function
x += 1; // Modify x again
println!("The value of x in main is {}.", x);
}