||Assigns a new name to referenced sub. If package specification is omitted in the name, then the current package is used. The return value is the sub. The name is only used for informative routines (caller, Carp, etc). You won't be able to actually invoke the sub by the given name. To allow that, you need to do glob-assignment yourself. Note that for anonymous closures (subs that reference lexicals declared outside the sub itself) you can name each instance of the closure differently, which can be very useful for debugging.