code: def import_sip04_data_all(data_filename):
      
      filename, fformat = os.path.splitext(data_filename)
  
      if fformat == '.csv':
          print('Import SIP04 data from .csv file')
          df_all = _import_csv_file(data_filename)
      elif fformat == '.mat':
          print('Import SIP04 data from .mat file')
          df_all = _import_mat_file(data_filename)
      else:
          print('Please use .csv or .mat format.')
          df_all = None
  
      return df_all
docs: Import ALL data from the result files
  
      Parameters
      ----------
      data_filename : string
          Path to .mat or .csv file containing SIP-04 measurement results. Note
          that the .csv file does not contain all data contained in the .mat
          file!
  
      Returns
      -------
      df_all : :py:class:`pandas.DataFrame`
          The data, contained in a DataFrame