code: def __generate_filepath(self):
          
          file_path = os.path.join(self.file_dir, str(uuid.uuid4()))
          if os.path.exists(file_path):
              warnings.warn("something has almost certainly gone wrong")
              return self.__generate_filepath()
          return file_path
docs: Generate a unique (absolute) file path within the file_dir directory
  
          :rtype: String
          :returns: a unique file path