Function parse 

pub fn parse(raw: &str) -> Result<SyncToken, MatrixError>

Parse a sync token back into its (stream_id, typing_gen) pair. Accepts the full s{stream_id}_{typing_gen} form [format] emits, the bare s{stream_id} form (typing_gen defaults to 0 — see the module doc), and a plain integer (a client that echoes a token verbatim never needs this leniency, but it costs nothing and matches routes::matrix::messaging’s own parse_stream_token leniency for the same reason).