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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def roles(self, roles_list):
        '''
        Set the roles for the current launch.

        Full list of roles can be found here:
        http://www.imsglobal.org/LTI/v1p1/ltiIMGv1p1.html#_Toc319560479

        LIS roles include:
        * Student
        * Faculty
        * Member
        * Learner
        * Instructor
        * Mentor
        * Staff
        * Alumni
        * ProspectiveStudent
        * Guest
        * Other
        * Administrator
        * Observer
        * None
        '''
        if roles_list and isinstance(roles_list, list):
            self.roles = [].extend(roles_list)
        elif roles_list and isinstance(roles_list, basestring):
            self.roles = [role.lower() for role in roles_list.split(',')]