Function seq_start 

pub fn seq_start(
    program: &str,
    macro_str: &str,
    bridge: &BlockingBridge,
    db: &PvDatabase,
) -> Result<(), String>

Start a std-module SNL program by name.

Name	Macros	Program
delayDo	P, R	delayDo.st — wait out an active condition, then process doSeq
femto	P, H, F, G1, G2, G3, NO	femto.st — Femto amplifier gain control

Must be called with the runtime reachable — from st.cmd that means CommandContext::bridge(), because the shell runs on a blocking thread.