from functools import wraps


def run_once(f):
    """Runs a function (successfully) only once.
    The running can be reset by setting the `has_run` attribute to False
    """

    @wraps(f)
    def wrapper(*args, **kwargs):
        if not wrapper.has_run:
            result = f(*args, **kwargs)
            wrapper.has_run = True
            wrapper.result = result
            return result
        else:
            return wrapper.result

    wrapper.has_run = False
    return wrapper