code: def phiforce(self,R,phi=0.,t=0.):
          
          return self._phiforce_nodecorator(R,phi=phi,t=t)
docs: NAME:
  
             phiforce
  
          PURPOSE:
  
             evaluate the phi force
  
          INPUT:
  
             R - Cylindrical radius (can be Quantity)
  
             phi= azimuth (optional; can be Quantity)
  
             t= time (optional; can be Quantity)
  
          OUTPUT:
  
             F_phi(R,(phi,t)))
  
          HISTORY:
  
             2010-07-13 - Written - Bovy (NYU)