Alone we can do so little, together we can do so much.
A method that invokes itself directly within its body is recursive, by definition. However, a recursive method does not necessarily have to call itself. It may call another one that in turn calls it back. Thus, invoking the method can provoke multiple calls to it. This type of recursion is called mutualRecursive!type!mutual or indirectRecursive!type!indirect.
In general, several methods are mutually recursive when they invoke themselves in a cyclical order. For instance, consider a set of methods . If calls , calls , and so on, and finally calls back