If 'flags' comes back as None, we use tools.run() otherwise use tools.run_flow(). The line this affects is the assignment of credentials in the if-block where we have to run through the flow. If argparse is indeed available, 'flags' will hold the ArgumentParser instance registered with the tools.argparser object as a parent. We now only need to use the sentinel to choose which "run" function to run, so to do that, replace this original line of code: