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: sancov_8bit.rs
    path of file: ./repos/LibAFL/libafl_targets/src
    
    the code of the file until where you have to start completion: //! [`LLVM` `8-bit-counters`](https://clang.llvm.org/docs/SanitizerCoverage.html#tracing-pcs-with-guards) runtime for `LibAFL`.
use alloc::vec::Vec;
use core::ptr::addr_of_mut;

use libafl_bolts::{ownedref::OwnedMutSlice, AsMutSlice, AsSlice};

/// A [`Vec`] of `8-bit-counters` maps for multiple modules.
/// They are initialized by calling [`__sanitizer_cov_8bit_counters_init`](
pub static mut COUNTERS_MAPS: Vec<OwnedMutSlice<'static, u8>> = Vec::new();

/// Create more copies of the counters maps
///
/// # Safety
/// You are responsible for ensuring there is no multi-mutability!
#[must_use]
pub unsafe fn extra_counters() -> Vec<OwnedMutSlice<'static, u8>> {
    COUNTERS_MAPS
        .iter()
        .map(|counters| {
            OwnedMutSlice::from_raw_parts_mut(
                counters.as_slice().as_ptr().cast_mut
    
pub extern "C" fn __sanitizer_cov_8bit_counters_init(start: *mut u8, stop: *mut u8) {
    unsafe {
        for existing in &mut *addr_of_mut!(COUNTERS_MAPS) {
            let range = existing.as_mut_slice().as_mut_ptr()
                ..=existing
                    .as_mut_slice()
                    .as_mut_ptr()
                    .add(existing.as_slice().len());
            if range.contains(&start) || range.contains(&stop) {
                // we have overlapping or touching ranges; merge them
                let &start = range.start().min(&start);
                let &stop = range.end().max(&stop);
                *existing =
                    OwnedMutSlice::from_raw_parts_mut(start, stop.offset_from(start) as usize);
                return;
            }
        }
        // we didn't overlap; keep going
        COUNTERS_MAPS.push(OwnedMutSlice::from_raw_parts_mut(
            start,
            stop.offset_from(start) as usize,
        ));
    }
}