code: def anglez(self,**kwargs): #pragma: no cover
          
          if hasattr(self,'_anglez'):
              return self._anglez
          zmax= self.calczmax()
          Ez= calcEz(self._z,self._vz,self._verticalpot)
          Tz= self.Tz(**kwargs)
          self._anglez= 2.*nu.pi*(nu.array(integrate.quad(_TzIntegrand,0.,nu.fabs(self._z),
                                                          args=(Ez,self._verticalpot),
                                                          **kwargs)))/Tz[0]
          if self._z >= 0. and self._vz >= 0.:
              pass
          elif self._z >= 0. and self._vz < 0.:
              self._anglez[0]= nu.pi-self._anglez[0]
          elif self._z < 0. and self._vz <= 0.:
              self._anglez[0]= nu.pi+self._anglez[0]
          else:
              self._anglez[0]= 2.*nu.pi-self._anglez[0]
          return self._anglez
docs: NAME:
             anglez
          PURPOSE:
             Calculate the vertical angle
          INPUT:
             +scipy.integrate.quad keywords
          OUTPUT:
             angle_z(z,vz)*vc/ro + estimate of the error
          HISTORY:
             2012-06-01 - Written - Bovy (IAS)