Function try_read_message 

pub fn try_read_message<R>(
    read: R,
    options: ReaderOptions,
) -> Result<Option<Reader<OwnedSegments>>>
where
    R: Read,

Like read_message(), but returns None instead of an error if there are zero bytes left in read.

This is useful for reading a stream containing an unknown number of messages – you call this function until it returns None.