use quick_error::quick_error; use crate::MAX_DATA_LEN; quick_error! {    /// The error returned by most functions in the [`encode`][crate::encode] module    #[derive(Debug)]    #[allow(missing_docs)]    pub enum Error {        DataLengthLimitExceeded(length_in_bytes: usize) {            display("Cannot encode more than {} bytes, got {}", MAX_DATA_LEN, length_in_bytes)        }        DataIsEmpty {            display("Empty lines are invalid")        }    }} #[cfg(all(not(feature = "blocking-io"), feature = "async-io"))]mod async_io;#[cfg(all(not(feature = "blocking-io"), feature = "async-io"))]pub use async_io::*; #[cfg(feature = "blocking-io")]mod blocking_io;#[cfg(feature = "blocking-io")]pub use blocking_io::*; pub(crate) fn u16_to_hex(value: u16) -> [u8; 4] {    let mut buf = [0u8; 4];    hex::encode_to_slice((value as u16).to_be_bytes(), &mut buf).expect("two bytes to 4 hex chars never fails");    buf}