def _need_snippet_displayed(overall_messages_dets, block_messages_dets, *,
    in_notebook=False, multi_block=False):
    """
    Don't need to see the code snippet displayed when it is already visible
    right next to it:
    * because in notebook (it is already in the cell straight above)
    * because there is only one block in snippet and there is a block message
      for it (which will display the block i.e. the entire snippet) UNLESS there
      is an overall message separating them
    Otherwise we need it displayed.
    """
    if in_notebook:
        return False
    mono_block_snippet = not multi_block
    if (mono_block_snippet and block_messages_dets and not
        overall_messages_dets):
        return False
    return True
