Thread Contexts
---------------
Every thread created by rep is a member of a "thread context", this
context is defined by the current position in the lisp call stack. At
any point in time, only threads which are members of the current
context may be executing.
- Function: call-with-dynamic-root thunk
Call the function of zero-parameters THUNK in a new thread
context. The new context will contain a single thread, that
executing THUNK.
The call to `call-with-dynamic-root' will only return once all
threads in the newly created context have been deleted, or a
non-local exit causes control to leave forcibly.