code: def FindFileByName(self, file_name):
      
  
      try:
        return self._file_descriptors[file_name]
      except KeyError:
        pass
  
      try:
        file_proto = self._internal_db.FindFileByName(file_name)
      except KeyError as error:
        if self._descriptor_db:
          file_proto = self._descriptor_db.FindFileByName(file_name)
        else:
          raise error
      if not file_proto:
        raise KeyError('Cannot find a file named %s' % file_name)
      return self._ConvertFileProtoToFileDescriptor(file_proto)
docs: Gets a FileDescriptor by file name.
  
      Args:
        file_name: The path to the file to get a descriptor for.
  
      Returns:
        A FileDescriptor for the named file.
  
      Raises:
        KeyError: if the file cannot be found in the pool.