Function phylofold::remove_small_bpps_from_bpp_mat

pub fn remove_small_bpps_from_bpp_mat(
    sparse_bpp_mat: &HashMap<(u16, u16), f64, BuildHasherDefault<FxHasher>>, 
    min_bpp: f64
) -> HashMap<(u16, u16), f64, BuildHasherDefault<FxHasher>>