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: add.rs
    path of file: ./repos/accel/accel/examples
    
    the code of the file until where you have to start completion: use accel::*;

#[kernel]
unsafe fn add(a: *const f32, b: *const f32, c: *mut f32, n: usize) {
    let i = accel_core::index();
    if (i as usize) < n {
        *c.offset(i) = *a.offset(i) + *b.offset(i);
    }
}

fn main() -> error::Result<()> {
    let device = Device::nth(0)?;
    let ctx = device.create_context();

    let _pf = Profiler::start(&ctx);

    // Allocate memories on GPU
    let n = 1024;
    let mut a = DeviceMemory::<f32>::zeros(&ctx, n);
    let mut 
    
fn main() -> error::Result<()> {
    let device = Device::nth(0)?;
    let ctx = device.create_context();

    let _pf = Profiler::start(&ctx);

    // Allocate memories on GPU
    let n = 1024;
    let mut a = DeviceMemory::<f32>::zeros(&ctx, n);
    let mut b = DeviceMemory::<f32>::zeros(&ctx, n);
    let mut c = DeviceMemory::<f32>::zeros(&ctx, n);

    // Accessible from CPU as usual Rust slice (though this will be slow)
    for i in 0..n {
        a[i] = i as f32;
        b[i] = 2.0 * i as f32;
    }

    // Launch kernel synchronously
    add(
        &ctx,
        1, /* grid */
        n, /* block */
        (a.as_ptr(), b.as_ptr(), c.as_mut_ptr(), n),
    )
    .expect("Kernel call failed");

    Ok(())
}