Decorate method with this to check whether the object has an attribute with the given name.

check_attr.py

def check(attr):
    def decorator(method):
        """
        Decorate method with this to check whether the object has an attribute with the given name.
        """

        @wraps(method)
        def wrapper(self, *args, **kwargs):
            if hasattr(self, attr):
                return method(self, *args, **kwargs)

            return None

        return wrapper

    return decorator