Function decode_with_receipts 

pub fn decode_with_receipts<BH, BB, R, E>(
    block: Result<BlockTuple, E>,
    decode_receipts: bool,
) -> Result<(BH, BB, Option<Vec<R>>)>
where
    BH: FullBlockHeader + Value,
    BB: FullBlockBody<OmmerHeader = BH>,
    R: RlpDecodableReceipt,
    E: From<E2sError> + Error + Send + Sync + 'static,

Like decode, but also extracts receipts when decode_receipts is true. receipts is Some whenever decode_receipts is true: era1’s CompressedReceipts entry is mandatory per spec, so (unlike .ere) it is never None just because the file omits it.