def _existing_file_path_option(option_name, option_value):
 file_path = FilePath(option_value)
 if (not file_path.exists()):
  raise UsageError(u"Problem with --{}. File does not exist: '{}'.".format(option_name, file_path.path))
 return file_path

def _existing_file_path_option ( option_name , option_value ) : file_path = FilePath ( option_value ) if ( not file_path . exists ( ) ) : raise UsageError ( u"Problem with --{}. File does not exist: '{}'." . format ( option_name , file_path . path ) ) return file_path
validate a command line option containing a filepath .