def get_package_url(cls, package, session=None, silent=False):
        response = get("{}/packages/{}".format(cls.bower_base_uri, package))
        return response.json().get("url", None)
def getAp2(self):
        ret =math.acos(((self.getLenp1() * self.getLenp1() + self.getLenp3() * self.getLenp3()) - self.getLenp2() * self.getLenp2()) / (2* self.getLenp1() * self.getLenp3()))
        return ret