transforms.py

class Transform:
    @staticmethod
    def to_lower(x):
        if x.isupper():
            return False
        return True

    @staticmethod
    def to_upper(x):
        if x.islower():
            return False
        return True

    @staticmethod
    def even_nums(x):
        if x % 2 == 0:
            return True
        return False

    @staticmethod
    def squires(x):
        return x**2

    @staticmethod
    def to_grade(x):
        if 90 <= x <= 100:
            return "A"
        elif 80 <= x < 90:
            return "B"
        elif 70 <= x < 80:
            return "C"
        elif 50 <= x < 70:
            return "D"
        return "F"


def main():
    nums = [1, 3, 8, 10, 7, 15]
    marks = [70, 93, 91, 80, 40, 50, 67, 83, 30]
    chars = "aBdEkeGlnMszX"
    t = Transform

    # using filter to get upper-letters just from chars
    char_list1 = list(filter(t.to_upper, chars))
    print(char_list1)

    # using filter to get lower-letters just from chars
    char_list2 = list(filter(t.to_lower, chars))
    print(char_list2)

    # using filter
    num_list = list(filter(t.even_nums, nums))
    print(num_list)

    # using map to evaluate marks
    marks = sorted(marks)  # this is used for sorting lists
    grades = list(map(t.to_grade, marks))
    print(grades)

    # using map to squire nums values
    num_list2 = list(map(t.squires, nums))
    print(num_list2)


if __name__ == '__main__':
    main()