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: lib.rs
    path of file: ./repos/Theseus/applications/pmu_sample_start/src
    
    the code of the file until where you have to start completion: //! This application is an example of how to start event based sampling using the
    
pub fn main(_args: Vec<String>) -> isize {
    if let Err(e) = pmu_x86::init() {
        println!("Could not initialize PMU: {:?}", e);
        return -1;
    }

    // run the pmu stat on this core
    /*let pmu = pmu_x86::stat::PerformanceCounters::new();
    match pmu {
        Ok(mut x) => {
            match x.end(){
                Ok(results) => println!("{:?}", results),
                Err(x) => println!("Results could not be retrieved for PMU stat: {:?}", x)
            }
        },
        Err(x) => println!("Could not create counters for PMU stat: {:?}", x)
    } */
    
    // run event based sampling on this core
    if let Err(e) = pmu_x86::start_samples(pmu_x86::EventType::UnhaltedReferenceCycles, 0xF_FFFF, None, 10) {
        println!("Could not start PMU sampling: {:?}", e);
        return -1;
    }

    0
}