code: function mustUnzip(file, mode){
    if (mode){
      return mode === 'tgz';
    }
    var extension = path.extname(file);
    return contains(['.tgz', '.gz'], extension);
  }
docs: Return true if the processed file must be unzipped.
  Check the mode and default to analyzing the file extension.
  
  @param file the processed file
  @param [mode] the mode
  @returns {Boolean} true if the file must be unzipped