code: def load_crmod_volt(self, filename):
          
          with open(filename, 'r') as fid:
              nr_of_configs = int(fid.readline().strip())
              measurements = np.loadtxt(fid)
              if nr_of_configs != measurements.shape[0]:
                  raise Exception(
                      'indicated number of measurements does not equal ' +
                      'to actual number of measurements')
          ABMN = self._crmod_to_abmn(measurements[:, 0:2])
          if self.configs is None:
              self.configs = ABMN
          else:
              # check that configs match
              if not np.all(ABMN == self.configs):
                  raise Exception(
                      'previously stored configurations do not match new ' +
                      'configurations')
  
          # add data
          cid_mag = self.add_measurements(measurements[:, 2])
          cid_pha = self.add_measurements(measurements[:, 3])
          return [cid_mag, cid_pha]
docs: Load a CRMod measurement file (commonly called volt.dat)
  
          Parameters
          ----------
          filename: string
              path to filename
  
          Returns
          -------
          list
              list of measurement ids