code: def pmll(self,*args,**kwargs):
          
          _check_roSet(self,kwargs,'pmll')
          _check_voSet(self,kwargs,'pmll')
          lbdvrpmllpmbb= self._lbdvrpmllpmbb(*args,**kwargs)
          return lbdvrpmllpmbb[:,4]
docs: NAME:
             pmll
          PURPOSE:
             return proper motion in Galactic longitude (in mas/yr)
          INPUT:
             t - (optional) time at which to get pmll
             obs=[X,Y,Z,vx,vy,vz] - (optional) position and velocity of observer 
                           (in kpc and km/s) (default=Object-wide default)
                           OR Orbit object that corresponds to the orbit
                           of the observer
                           Y is ignored and always assumed to be zero
             ro= distance in kpc corresponding to R=1. (default=Object-wide default)         
             vo= velocity in km/s corresponding to v=1. (default=Object-wide default)
          OUTPUT:
             pm_l(t) in mas/yr
          HISTORY:
             2011-02-24 - Written - Bovy (NYU)