code: def _getcosmoheader(cosmo):
      
  
      cosmoheader = ("# Cosmology (flat) Om:{0:.3f}, Ol:{1:.3f}, h:{2:.2f}, "
                     "sigma8:{3:.3f}, ns:{4:.2f}".format(
                         cosmo['omega_M_0'], cosmo['omega_lambda_0'], cosmo['h'],
                         cosmo['sigma_8'], cosmo['n']))
  
      return(cosmoheader)
docs: Output the cosmology to a string for writing to file