code: def add_user(
              self, user,
              first_name=None, last_name=None,
              email=None, password=None
          ):
          
          self.project_service.set_auth(self._token_project)
          self.project_service.add_user(
              user, first_name, last_name, email, password)
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.