docs: def create_db(self, app):
          """Create a ZODB connection pool from the *app* configuration."""
          assert 'ZODB_STORAGE' in app.config, \
                 'ZODB_STORAGE not configured'
          storage = app.config['ZODB_STORAGE']
          if isinstance(storage, basestring):
              factory, dbargs = zodburi.resolve_uri(storage)
          elif isinstance(storage, tuple):
              factory, dbargs = storage
          else:
              factory, dbargs = storage, {}
          return DB(factory(), **dbargs)