<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def is_downloaded(self):
 """ Checks if data for this request has already been downloaded and is saved to disk. :return: returns ``True`` if data for this request has already been downloaded and is saved to disk. :rtype: bool """

        if self.file_path is None:
            return False
        return os.path.exists(self.file_path)