trigger a job

def _trigger_job(job):
    """ trigger a job """
    if job.api_instance().is_running():
        return "{0}, {1} is already running".format(job.host, job.name)
    else:
        requests.get(job.api_instance().get_build_triggerurl())
        return "triggering {0}, {1}...".format(job.host, job.name)