A simple loop form is one that has a body containing only compound forms. Each form is evaluated in turn from left to right. When the last form has been evaluated, then the first form is evaluated again, and so on, in a never-ending cycle. A simple loop form establishes an implicit block named nil. The execution of a simple loop can be terminated by explicitly transfering control to the implicit block (using return or return-from) or to some exit point outside of the block (e.g., using throw, go, or return-from).