Function decode_frontier 

pub fn decode_frontier<F>(
    base_offset: usize,
    bytes: &[u8],
    rules: &DecodeRules,
    decode_one: &mut F,
    state: &mut FrontierState<'_>,
) -> Result<()>
where
    F: FnMut(DecodeFormat, &[u8], &DecodeRules) -> Result<Vec<DecodedRegion>>,

decode_frontier function.