Use += and -=
Use -= for odd case
Introduce ItemWrapper delegator
Extract body of update to ItemWrapper
Inline GildedRose#update
Inline item temp
Remove redundant self. qualifiers
Extract increase_quality
Swap independent conditions
Extract decrease_quality
Un-nest conditional
Use increase_quality one more time
Move sell_in adjustment to top
Extract age
Extract update_quality
Use positive logic for top conditional
Use positive logic for second conditional
Use positive logic for last conditional
Use if..elsif
Extract Sulfuras to a guard clause