code: def _format_credentials(self):
          
          if self._creds_style == "apikey":
              return {"auth": {"RAX-KSKEY:apiKeyCredentials":
                      {"username": "%s" % self.username,
                      "apiKey": "%s" % self.api_key}}}
          else:
              # Return in the default password-style
              return super(RaxIdentity, self)._format_credentials()
docs: Returns the current credentials in the format expected by the
          authentication service. Note that by default Rackspace credentials
          expect 'api_key' instead of 'password'. However, if authentication
          fails, return the creds in standard password format, in case they are
          using a username / password combination.