decorators3.py

def restricted(f):
    def decorated_f(user):
        if user is None or not user.is_admin:
            return None
        return f(user)
    return decorated_f

[...]

@restricted
def userlist(user):
    return 'This is the whole registered user list. [Sensitive data]'

@restricted
def inventory(user):
    return 'This is the inventory resource. [Sensitive data]'