Exit implements the logic related to modeling and scheduling thread termination.

Cleanup destroys the existing instance of the tester.

Setup sets up a new instance of the tester.

Start implements the logic related to modeling and scheduling an execution of "go fn()".

T returns the global instance of the tester.

TIDGenerator is used for generating unique thread identifiers.

Tester represents an instance of the systematic test.

IncreasingDepth is used to sort states in the increasing order of their depth.

Increasing is used to sort thread identifiers in an increasing order.

TID is the thread identifier type.