old_contents: # Licensed under a 3-clause BSD style license - see PYFITS.rst
  from __future__ import absolute_import
  
  from distutils.core import Extension
  from astropy_helpers import setup_helpers
  
  def get_extensions():
      # Get gary path
      import os
      import gary
      gary_base_path = os.path.split(gary.__file__)[0]
      gary_incl_path = os.path.join(gary_base_path, "potential")
  
      cfg = setup_helpers.DistutilsExtensionArgs()
      cfg['include_dirs'].append('numpy')
      cfg['include_dirs'].append(gary_incl_path)
      cfg['sources'].append('ophiuchus/potential/core.pyx')
      cfg['sources'].append('ophiuchus/potential/src/_potential.c')
      cfg['sources'].append(os.path.join(gary_incl_path, '_cbuiltin.c'))
      cfg['libraries'] = ['gsl', 'gslcblas']
  
      return [Extension('ophiuchus.potential._potential', **cfg)]
  
new_contents: # Licensed under a 3-clause BSD style license - see PYFITS.rst
  from __future__ import absolute_import
  
  import os
  from distutils.core import Extension
  from astropy_helpers import setup_helpers
  
  def get_extensions():
      # Get gary path
      import gary
      gary_base_path = os.path.split(gary.__file__)[0]
      gary_incl_path = os.path.join(gary_base_path, "potential")
  
      # Get biff path
      import biff
      biff_base_path = os.path.split(biff.__file__)[0]
      biff_incl_path = os.path.join(biff_base_path, "src")
      print(biff_incl_path)
  
      cfg = setup_helpers.DistutilsExtensionArgs()
      cfg['include_dirs'].append('numpy')
      cfg['include_dirs'].append(gary_incl_path)
      cfg['include_dirs'].append(biff_incl_path)
      cfg['sources'].append('ophiuchus/potential/core.pyx')
      cfg['sources'].append('ophiuchus/potential/src/_potential.c')
      cfg['sources'].append(os.path.join(gary_incl_path, '_cbuiltin.c'))
      cfg['sources'].append(os.path.join(biff_incl_path, 'bfe.c'))
      cfg['sources'].append(os.path.join(biff_incl_path, 'bfe_helper.c'))
      cfg['libraries'] = ['gsl', 'gslcblas']
  
      return [Extension('ophiuchus.potential._potential', **cfg)]
  
subject: add source from biff