docs: def prompt_auth(self):
          """Prompt the user for login/pass, if needed."""
          if self.username and self.password:
              return
          sys.stdout.write("Please insert your credentials for %s\n" % self.url.base_url)
          while not self.username:
              self.username = raw_input("Username [%s]: " % getpass.getuser())
  
          while not self.password:
              self.password = getpass.getpass("Password: ")