def scan(
      self,
      selector_fn: Callable[[str], bool],
  ) -> Sequence[str]:
    """Retrieves selected memories.

    Args:
      selector_fn: The selector function that returns True for memories to
        retrieve.

    Returns:
      A list of memory results, sorted by their recency.
    """
    raise NotImplementedError()
Retrieves selected memories.

    Args:
      selector_fn: The selector function that returns True for memories to
        retrieve.

    Returns:
      A list of memory results, sorted by their recency.
    
concordia/components/agent/memory.py