code: def calcEscapecurve(Pot,Rs):
      
      isList= isinstance(Pot,list)
      isNonAxi= ((isList and Pot[0].isNonAxi) or (not isList and Pot.isNonAxi))
      if isNonAxi:
          raise AttributeError("Escape velocity curve plotting for non-axisymmetric potentials is not currently supported")
      try:
          grid= len(Rs)
      except TypeError:
          grid=1
          Rs= nu.array([Rs])
      esccurve= nu.zeros(grid)
      for ii in range(grid):
          esccurve[ii]= vesc(Pot,Rs[ii],use_physical=False)
      return esccurve
docs: NAME:
         calcEscapecurve
      PURPOSE:
         calculate the escape velocity curve for this potential (in the 
         z=0 plane for non-spherical potentials)
      INPUT:
         Pot - Potential or list of Potential instances
  
         Rs - (array of) radius(i)
      OUTPUT:
         array of v_esc
      HISTORY:
         2011-04-16 - Written - Bovy (NYU)