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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 is_role(self, role):
 """ Verify if user is in role :param: role: role to verify against :return: if user is in role :exception: LTIException if role is unknown """

        log.debug("is_role %s", role)
        roles = self.session['roles'].split(',')
        if role in LTI_ROLES:
            role_list = LTI_ROLES[role]
            # find the intersection of the roles
            roles = set(role_list) & set(roles)
            is_user_role_there = len(roles) >= 1
            log.debug(
                "is_role roles_list=%s role=%s in list=%s", role_list,
                roles, is_user_role_there
            )
            return is_user_role_there
        else:
            raise LTIException("Unknown role {}.".format(role))