def getProcessOutputAndValue(executable, args=(), env={}, path=None,
                             reactor=None, stdinBytes=None):
    """Spawn a process and returns a Deferred that will be called back with
    its output (from stdout and stderr) and it's exit code as (out, err, code)
    If a signal is raised, the Deferred will errback with the stdout and
    stderr up to that point, along with the signal, as (out, err, signalNum)
    """
    return _callProtocolWithDeferred(
        _EverythingGetter,
        executable,
        args,
        env,
        path,
        reactor,
        protoArgs=(stdinBytes,),
    )
Spawn a process and returns a Deferred that will be called back with
    its output (from stdout and stderr) and it's exit code as (out, err, code)
    If a signal is raised, the Deferred will errback with the stdout and
    stderr up to that point, along with the signal, as (out, err, signalNum)
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/utils.py