def add_flow_exception(exc):
  global _flow_exceptions
  if not isinstance(exc, type) or not issubclass(exc, Exception):
    raise TypeError('Expected an Exception subclass, got %r' % (exc,))
  as_set = set(_flow_exceptions)
  as_set.add(exc)
  _flow_exceptions = tuple(as_set)
Add an exception that should not be logged.
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/ndb/tasklets.py/add_flow_exception