code: def Tphi(self,**kwargs): #pragma: no cover
          
          if hasattr(self,'_Tphi'):
              return self._Tphi
          (rperi,rap)= self.calcRapRperi(**kwargs)
          if rap == rperi:#Circular orbit
              return 2.*m.pi*self._R/self._vT
          TR= self.TR(**kwargs)
          I= self.I(**kwargs)
          Tphi= TR/I*m.pi
          self._Tphi= Tphi
          return self._Tphi
docs: NAME:
             Tphi
          PURPOSE:
             Calculate the azimuthal period
          INPUT:
             +scipy.integrate.quadrature keywords
          OUTPUT:
             T_phi(R,vT,vT)/ro/vc + estimate of the error
          HISTORY:
             2010-12-01 - Written - Bovy (NYU)