function
boot.janet on line 1514, column 1
(update ds key func & args)
For a given key in data structure `ds`, replace its corresponding
value with the result of calling `func` on that value. If `args`
are provided, they will be passed along to `func` as well. Returns
`ds`, updated.
(-> @{:a 0 :b 0}
(update :a inc)
(update :b inc))
# => @{:a 1 :b 1}
(update @{:a 1} :a inc)
# => @{:a 2}
(update @[3 4 5] 1 dec) # => @[3 3 5]
(update (update @[3 4 5] 1 dec) 2 inc) # => @[3 3 6]