code: def vterm(Pot,l,deg=True):
      
      Pot= flatten(Pot)
      if _APY_LOADED and isinstance(l,units.Quantity):
          l= l.to(units.rad).value
          deg= False
      if deg:
          sinl= nu.sin(l/180.*nu.pi)
      else:
          sinl= nu.sin(l)
      return sinl*(omegac(Pot,sinl,use_physical=False)
                   -omegac(Pot,1.,use_physical=False))
docs: NAME:
      
          vterm
          
      PURPOSE:
      
          calculate the terminal velocity at l in this potential
  
      INPUT:
      
          Pot - Potential instance
      
          l - Galactic longitude [deg/rad; can be Quantity)
          
          deg= if True (default), l in deg
          
      OUTPUT:
          
          terminal velocity
          
      HISTORY:
          
          2013-05-31 - Written - Bovy (IAS)