Strategy for signaling an operation after a timeout expires.
An instance of this trait is used for configuration when using traits
TimeLimits and TimeLimitedTests.
Signals an operation.
This method may do anything to attempt to signal or interrupt an operation, or even do nothing.
When called by failAfter method of trait TimeLimits, the passed
Thread will represent the main test thread. This Thread is
passed in case it is useful, but need not be used by implementations of this method.