def memoize_method(method):
    """Simple caching decorator."""
    cache = {}

    @functools.wraps(method)
    def wrapper(self, *args, **kwargs):
        """Caching wrapper."""
        key = (args, tuple(sorted(kwargs.items())))
        if key in cache:
            return cache[key]
        else:
            result = method(self, *args, **kwargs)
            cache[key] = result
            return result

    return wrapper