You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: old.rs
    path of file: ./repos/c2rust/c2rust-refactor/tests/expr_parens_2
    
    the code of the file until where you have to start completion: /// Test case for checking the rewriter's handling of operator precedence.  The `test_one_plus_one`
/// and `test_f_plus_one` rewrites should both be semantics-preserving on this program.
    
fn main() {
    println!("f(2) = {}", f(2));

    println!("2 + 10 = {}", 2 + 10);
    println!("10 + 2 = {}", 10 + 2);
    println!("2 + 2 = {}", 2 + 2);
    // Higher precedence than +
    println!("2 * 10 = {}", 2 * 10);
    println!("10 * 2 = {}", 10 * 2);
    // Lower precedence than +
    println!("2 << 3 = {}", 2 << 3);
    println!("3 << 2 = {}", 3 << 2);

    println!("f(2 + 3) = {}", f(2 + 3));
    println!("f(2 * 3) = {}", f(2 * 3));
    println!("f(2 << 3) = {}", f(2 << 3));
}