code: def retrieve_all(self, sids, default_none=False):
          
  
          failures = set()
          hits = {}
          for sid in sids:
              try:
                  hits[sid] = self._asset_cache[sid]
              except KeyError:
                  if not default_none:
                      failures.add(sid)
                  else:
                      hits[sid] = None
  
          if len(failures) > 0:
              raise SidsNotFound(sids=list(failures))
  
          return [hits[sid] for sid in sids]
docs: Retrieve all assets in `sids`.
  
          Parameters
          ----------
          sids : iterable of string
              Assets to retrieve.
          default_none : bool
              If True, return None for failed lookups.
              If False, raise `SidsNotFound`.
  
          Returns
          -------
          assets : list[Asset or None]
              A list of the same length as `sids` containing Assets (or Nones)
              corresponding to the requested sids.
  
          Raises
          ------
          SidsNotFound
              When a requested sid is not found and default_none=False.