code: def pmll(self,*args,**kwargs):
          
          out= self._orb.pmll(*args,**kwargs)
          if len(out) == 1: return out[0]
          else: return out
docs: NAME:
  
             pmll
  
          PURPOSE:
  
             return proper motion in Galactic longitude (in mas/yr)
  
          INPUT:
  
             t - (optional) time at which to get pmll (can be Quantity)
  
  v           obs=[X,Y,Z,vx,vy,vz] - (optional) position and velocity of observer 
                           in the Galactocentric frame
                           (in kpc and km/s) (default=[8.0,0.,0.,0.,220.,0.]; entries can be Quantities)
                           OR Orbit object that corresponds to the orbit
                           of the observer
                           Y is ignored and always assumed to be zero
  
             ro= (Object-wide default) physical scale for distances to use to convert (can be Quantity)
  
             vo= (Object-wide default) physical scale for velocities to use to convert (can be Quantity)
  
          OUTPUT:
  
             pm_l(t) in mas/yr
  
          HISTORY:
  
             2011-02-24 - Written - Bovy (NYU)