code: def Rforce(self,R,z,phi=0.,t=0.,v=None):
          
          return self._Rforce_nodecorator(R,z,phi=phi,t=t,v=v)
docs: NAME:
  
             Rforce
  
          PURPOSE:
  
             evaluate cylindrical radial force F_R  (R,z)
  
          INPUT:
  
             R - Cylindrical Galactocentric radius (can be Quantity)
  
             z - vertical height (can be Quantity)
  
             phi - azimuth (optional; can be Quantity)
  
             t - time (optional; can be Quantity)
  
             v - 3d velocity (optional; can be Quantity)
  
          OUTPUT:
  
             F_R (R,z,phi,t,v)
  
          HISTORY:
  
             2018-03-18 - Written - Bovy (UofT)