This is a test to make sure you can get and set values in SessionStorage by index.
Setting FOO using the index setter.
Reading FOO:
BAR
BAR
BAR

Setting FOO again, using setItem.
Reading FOO:
BAZ
BAZ
BAZ

Setting FOO again, using the index setter.
Reading FOO:
BAT
BAT
BAT

Setting FOO again, using property-slot syntax
Reading FOO:
BATMAN
BATMAN
BATMAN

Removing FOO, then trying to read it
Reading FOO:
undefined
undefined
null