Function run_process 

pub fn run_process<I, S>(
    program: impl Into<String>,
    args: I,
) -> Operator<ProcessResult>
where
    I: IntoIterator<Item = S>,
    S: Into<String>,

run_process: execute one process via the graph-local environment process driver.

Completion emits one ProcessResult DATA and COMPLETE. Non-zero process exits remain DATA. Driver/spawn failures become protocol ERROR.