Function neofold::remove_small_bpps_from_bpp_mat

pub fn remove_small_bpps_from_bpp_mat(
    sparse_bpp_mat: &HashMap<(usize, usize), f64, BuildHasherDefault<FnvHasher>>, 
    min_bpp: f64
) -> HashMap<(usize, usize), f64, BuildHasherDefault<FnvHasher>>