code: def write_mnefiff(data, filename):
      
      from mne import create_info, set_log_level
      from mne.io import RawArray
  
      set_log_level(WARNING)
  
      TRIAL = 0
      info = create_info(list(data.axis['chan'][TRIAL]), data.s_freq, ['eeg', ] *
                         data.number_of('chan')[TRIAL])
  
      UNITS = 1e-6  # mne wants data in uV
      fiff = RawArray(data.data[0] * UNITS, info)
  
      if data.attr['chan']:
          fiff.set_channel_positions(data.attr['chan'].return_xyz(),
                                     data.attr['chan'].return_label())
  
      fiff.save(filename, overwrite=True)
docs: Export data to MNE using FIFF format.
  
      Parameters
      ----------
      data : instance of ChanTime
          data with only one trial
      filename : path to file
          file to export to (include '.mat')
  
      Notes
      -----
      It cannot store data larger than 2 GB.
      The data is assumed to have only EEG electrodes.
      It overwrites a file if it exists.