Returns an array of user ids for users on the filesystem

def local_users(self):
        """Returns an array of user ids for users on the filesystem"""
        # Any users on the machine will have an entry inside of the userdata
        # folder. As such, the easiest way to find a list of all users on the
        # machine is to just list the folders inside userdata
        userdirs = filter(self._is_user_directory, os.listdir(self.userdata_location()))
        # Exploits the fact that the directory is named the same as the user id
        return map(lambda userdir: user.User(self, int(userdir)), userdirs)