All pushes and unshifts cause the elements in question to be inserted in
the appropriate location to maintain order.
Direct stores ($a[10] = "wibble") effectively splice out the original
value and insert the new element. It's not clear why you'd want to use
direct stores like that, but this module does the right thing if you do.
WWW: http://search.cpan.org/dist/Tie-Array-Sorted/
