async def get_credentials(self, image, tag):
        """
        If a dynamic token is required for pushing an image to the registry
        return a dictionary of login credentials, otherwise return None
        (caller should get credentials from some other source)
        """
        return None

        If a dynamic token is required for pushing an image to the registry
        return a dictionary of login credentials, otherwise return None
        (caller should get credentials from some other source)
        
binderhub/registry.py