code: def make_ecc_interpolant():
      
      pth = resource_filename(Requirement.parse('libstempo'),
                              'libstempo/ecc_vs_nharm.txt')
  
      fil = np.loadtxt(pth)
  
      return interp1d(fil[:,0], fil[:,1])
docs: Make interpolation function from eccentricity file to
      determine number of harmonics to use for a given
      eccentricity.
  
      :returns: interpolant