code: def convert_meas_df_thellier_gui(meas_df_in, output):
      
      output = int(output)
      meas_mapping = get_thellier_gui_meas_mapping(meas_df_in, output)
      meas_df_out = meas_df_in.rename(columns=meas_mapping)
      if 'measurement' not in meas_df_out.columns:
          meas_df_out['measurement'] = meas_df_in['measurement']
      return meas_df_out
docs: Take a measurement dataframe and convert column names
      from MagIC 2 --> 3 or vice versa.
      Use treat_step_num --> measurement_number if available,
      otherwise measurement --> measurement_number.
  
      Parameters
      ----------
      meas_df_in : pandas DataFrame
          input dataframe with measurement data
      output : int
          output to MagIC 2 or MagIC 3