class Course:

    def __init__(self, name, units, status, score):
        self.name = name    # name of the course
        self.units = units  # number of units the course weighs
        self.status = status # can assume C, R or E
        self.score = score  # the score achieved in the course

    @property
    def wgpa(self):
        return self.gpa * self.units

    @property
    def gpa(self):
        '''Return the gpa weight of the course.
        Computed from the score of course object.'''

        if is_between(self.score, 70, 100):
            return 7.0
        elif is_between(self.score, 65, 69):
            return 6.0
        elif is_between(self.score, 60, 64):
            return 5.0
        elif is_between(self.score, 55, 59):
            return 4.0
        elif is_between(self.score, 50, 54):
            return 3.0
        elif is_between(self.score, 45, 49):
            return 2.0
        elif is_between(self.score, 40, 44):
            return 1.0
        elif is_between(self.score, 0, 39):
            return 0.0
        else:
            raise ValueError("You entered an invalid score!")