code: def read_resfile(resfile):
          
          assert os.path.exists(resfile),"read_resfile() error: resfile " +\
                                         "{0} not found".format(resfile)
          converters = {"name": str_con, "group": str_con}
          f = open(resfile, 'r')
          while True:
              line = f.readline()
              if line == '':
                  raise Exception("Pst.get_residuals: EOF before finding "+
                                  "header in resfile: " + resfile)
              if "name" in line.lower():
                  header = line.lower().strip().split()
                  break
          res_df = pd.read_csv(f, header=None, names=header, sep="\s+",
                                   converters=converters)
          res_df.index = res_df.name
          f.close()
          return res_df
docs: load a residual file into a pandas.DataFrame
  
          Parameters
          ----------
          resfile : str
              residual file name
  
          Returns
          -------
          pandas.DataFrame : pandas.DataFrame