The type of modes of events delivery.

Returns a mode delivering events as soon as they are generated.

Returns a mode delivering all events at program termination.

Returns a mode delivering events every time a condition, specified by the string parameter is made true. The condition can have one of the following form:

• an integer followed by the letter 'e' (e. g. "10e") means that events are delivered when n have been accumulated;
• an integer followed by the letter 'b' (e. g. "10b") means that events are delivered when a string representation of n bytes has been accumulated;
• an integer followed by the letter 's' (e. g. "10s") means that events are delivered every n seconds.