code: def _Open(self, path_spec=None, mode='rb'):
      
      if not path_spec:
        raise ValueError('Missing path specification.')
  
      if path_spec.HasParent():
        raise errors.PathSpecError('Unsupported path specification with parent.')
  
      location = getattr(path_spec, 'location', None)
      if location is None:
        raise errors.PathSpecError('Path specification missing location.')
  
      self._current_offset = 0
      self._size = len(self._file_data)
docs: Opens the file-like object defined by path specification.
  
      Args:
        path_spec (PathSpec): path specification.
        mode (Optional[str]): file access mode.
  
      Raises:
        AccessError: if the access to open the file was denied.
        IOError: if the file-like object could not be opened.
        OSError: if the file-like object could not be opened.
        PathSpecError: if the path specification is incorrect.
        ValueError: if the path specification is invalid.