class KlassPublisher:

    def register(self, observer):
        pass

    def unregister(self, observer):
        pass


class KlassInfo:

    def __init__(self, name, klass_number, is_leader):
        self.name = name
        self.klass_number = klass_number
        self.is_leader = is_leader


class KlassObserver:

    def update(self, student_info: KlassInfo):
        pass

37ad17906e8f6486789cb9eba5d8861aa4ce95a7
<mask token>


class KlassInfo:
    <mask token>


class KlassObserver:

    def update(self, student_info: KlassInfo):
        pass

<mask token>


class KlassInfo:

    def __init__(self, name, klass_number, is_leader):
        self.name = name
        self.klass_number = klass_number
        self.is_leader = is_leader


class KlassObserver:

    def update(self, student_info: KlassInfo):
        pass

class KlassPublisher:

    def register(self, observer):
        pass
    <mask token>


class KlassInfo:

    def __init__(self, name, klass_number, is_leader):
        self.name = name
        self.klass_number = klass_number
        self.is_leader = is_leader


class KlassObserver:

    def update(self, student_info: KlassInfo):
        pass

class KlassPublisher:

    def register(self, observer):
        pass

    def unregister(self, observer):
        pass


class KlassInfo:

    def __init__(self, name, klass_number, is_leader):
        self.name = name
        self.klass_number = klass_number
        self.is_leader = is_leader


class KlassObserver:

    def update(self, student_info: KlassInfo):
        pass
