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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def modify_user_power_levels(self, users=None, users_default=None):
 """Modify the power level for a subset of users Args: users(dict):
 Power levels to assign to specific users, in the form {"@name0:host0": 10, "@name1:host1": 100, "@name3:host3", None} A level of None causes the user to revert to the default level as specified by users_default. users_default(int):
 Default power level for users in the room Returns: True if successful, False if not """

        try:
            content = self.client.api.get_power_levels(self.room_id)
            if users_default:
                content["users_default"] = users_default

            if users:
                if "users" in content:
                    content["users"].update(users)
                else:
                    content["users"] = users

                # Remove any keys with value None
                for user, power_level in list(content["users"].items()):
                    if power_level is None:
                        del content["users"][user]
            self.client.api.set_power_levels(self.room_id, content)
            return True
        except MatrixRequestError:
            return False