code: def _get_file_version(filename):
      
      mat = sio.loadmat(filename, squeeze_me=True)
      version = mat['MP']['Version'].item()
      del(mat)
  
      return version
docs: High level import function that tries to determine the specific version
      of the data format used.
  
      Parameters
      ----------
      filename: string
          File path to a .mat matlab filename, as produced by the various
          versions of the emmt_pp.exe postprocessing program.
  
      Returns
      -------
      version: string
          a sanitized version of the file format version