docs: def _remove_from(self, db, index, item):
          """
          Remove `item` from `db` at `index`.
  
          Note:
              This function is inverse to :meth:`._add_to`.
  
          Args:
              db (dict-obj): Dict-like object used to connect to database.
              index (str): Index used to look in `db`.
              item (obj): Persistent object, which may be stored in DB.
          """
          with transaction.manager:
              row = db.get(index, None)
  
          if row is None:
              return
  
          with transaction.manager:
              if item in row:
                  row.remove(item)
  
          with transaction.manager:
              if not row:
                  del db[index]