Student_group

class Human:

    def __init__(self, gender, age, first_name, last_name):
        self.gender = gender
        self.age = age
        self.first_name = first_name
        self.last_name = last_name

    def __str__(self):
        return f'{self.first_name} {self.last_name}, age:{self.age}, gender:{self.gender}'



class Student(Human):

    def __init__(self, gender, age, first_name, last_name, record_book):
        super().__init__(gender, age, first_name, last_name)
        self.record_book = record_book

    def __str__(self):
        return f'{super().__str__()}, {self.record_book}'


class Group:
    def __init__(self, number):
        self.number = number
        self.group = set()

    def add_student(self, student):
        self.group.add(student)

    def delete_student(self, last_name):
        res = self.find_student(last_name)
        self.group.discard(res)


    def find_student(self, last_name):
        for student in self.group:
            if student.last_name == last_name:
                return student
        return None

    def __str__(self):
        all_students = ''
        for student in self.group:
            all_students += f'{str(student)}\n'
        return f'Number:{self.number}\n{all_students} '


st1 = Student('Male', 30, 'Steve', 'Jobs', 'AN142')
st2 = Student('Female', 25, 'Liza', 'Taylor', 'AN145')
gr = Group('PD1')
gr.add_student(st1)
gr.add_student(st2)
print(gr)
gr.find_student('Jobs') 
gr.find_student('Jobs2')  # None

gr.delete_student('Taylor')
print(gr) # Only one student