new_contents: # coding: utf-8
  
  """ Potential used for Pal 5 Challenge at the Gaia Challenge 2 """
  
  from __future__ import division, print_function
  
  __author__ = "adrn <adrn@astro.columbia.edu>"
  
  # Third-party
  from astropy.constants import G
  import numpy as np
  
  # Project
  # from .core import CartesianCompositePotential
  from .cpotential import CCompositePotential
  from .cbuiltin import HernquistPotential, MiyamotoNagaiPotential, Pal5AxisymmetricNFWPotential
  from ..units import galactic
  
  __all__ = ['GC2Pal5Potential']
  
  # change to CartesianCompositePotential for Pure-Python
  class GC2Pal5Potential(CCompositePotential):
  
      def __init__(self, m_disk=6.5E10, a=6.5, b=0.26,
                   m_spher=2E10, c=0.3,
                   m_halo=1.81194E12, Rh=32.26, qz=0.814,
                   units=galactic):
  
          # Choice of v_h sets circular velocity at Sun to 220 km/s
          self.units = units
  
          kwargs = dict()
          kwargs["disk"] = MiyamotoNagaiPotential(units=units,
                                                  m=m_disk, a=a, b=b)
  
          kwargs["bulge"] = HernquistPotential(units=units,
                                               m=m_spher, c=c)
  
          kwargs["halo"] = Pal5AxisymmetricNFWPotential(units=units,
                                                        M=m_halo, Rh=Rh, qz=qz)
          super(GC2Pal5Potential,self).__init__(**kwargs)
          self.c_instance.G = G.decompose(units).value
  
subject: add python class for composite potential