# def fac(x,y=2):
#     return x**y
# list = [1,2,3]
# list2 =[]
# for i in range(len(list)):
#     list[i] = fac(list[i])
# print (list)


class Lecture:
    def __init__(self, title):
        """
        Initializes a new Lecture instance with a title and an empty list of students.

        :param title: Title of the lecture
        """
        self.title = title
        self.students = []

    def add_student(self, student_name):
        """
        Adds a student to the lecture.

        :param student_name: Name of the student to be added
        """
        if student_name not in self.students:
            self.students.append(student_name)
            print(f"{student_name} has been added to the lecture '{self.title}'.")
        else:
            print(f"{student_name} is already enrolled in the lecture '{self.title}'.")

    def number_of_students(self):
        """
        Returns the number of students enrolled in the lecture.

        :return: The count of students
        """
        return len(self.students)


# Example usage

# Create a new lecture
python_lecture = Lecture("Introduction to Python")
# Add students
python_lecture.add_student("Alice")
python_lecture.add_student("Bob")
python_lecture.add_student("Alice")  # Attempt to add Alice again

# Get the number of students
print(f"Number of students enrolled in '{python_lecture.title}': {python_lecture.number_of_students()}")