             ",".join(current_path),
             json.dumps(v)
           ).strip()
+
         elif k == '$notin':
           if type(v) is not list:
             plpy.error("Value of '$notin' operator must be an array")

            ",".join(current_path),
            json.dumps(v)
          ).strip()
        elif k == '$exists':
          if type(v) is not bool:
            plpy.error("Value of '$exists' operator must be a boolean")

            s = "bq_jdoc #> '{{{}}}' is null".format(
              ",".join(current_path),
            ).strip()

        else:
          plpy.error("Invalid query operator: {}".format(k))
        special_queries.append(s)
