code: def add_file(self, file, **kwargs):
          
  
          if os.access(file, os.F_OK):
  
              if file in self.f_repository:
                  raise DuplicationError("file already added.")
  
              self.f_repository.append(file)
  
          else:
              raise IOError("file not found.")
docs: Append a file to file repository.
  
          For file monitoring, monitor instance needs file.
          Please put the name of file to `file` argument.
  
          :param file: the name of file you want monitor.