code: def add_user(
          self, user, first_name=None, last_name=None, email=None, password=None):
          
          self.service.add_user(
              user, first_name, last_name, email, password,
              self.url_prefix, self.auth, self.session, self.session_send_opts)
docs: Add a new user.
  
          Args:
              user (string): User name.
              first_name (optional[string]): User's first name.  Defaults to None.
              last_name (optional[string]): User's last name.  Defaults to None.
              email: (optional[string]): User's email address.  Defaults to None.
              password: (optional[string]): User's password.  Defaults to None.
  
          Raises:
              requests.HTTPError on failure.