module to manipulate upper scopes

 Scope::Upper is a Perl module that provides a way for Perl programs to defer
 actions at run-time until the control flow returns to the upper scope. It
 currently enables developers to:
 .
  * Hook an upper scope end with "reap"
  * Localize variables, array/hash values or deletions of elements in
    higher contexts with respectively "localize", "localize_elem" and
    "localize_delete"
  * Return values immediately to an upper level with "unwind", and know
    which context was in use then with "want_at"