Unload a given module or reload it from its source.
unload(mod)reload(mod)
the module reference to be unloaded or reloaded
box::unload and box::reload are called for their
side-effect. They do not return anything.
Unloading a module causes it to be purged from the internal cache such that
the next subsequent box::use declaration will reload the module from
its source. reload is a shortcut for unloading a module and calling
box::use in the same scope with the same parameters as the
box::use call that originally loaded the current module instance.