function
boot.janet on line 1069, column 1
(index-of x ind &opt dflt)
Find the first key associated with a value x in a data structure,
acting like a reverse lookup. Will not look at table prototypes.
Returns `dflt` if not found.
# in struct
(index-of 2 {:a 1 :b 2 :c 3 :d 2} )
# => :b
# in table
(index-of 2 @{:a 1 :b 2 :c 3 :d 2})
# => :b
# in array
(index-of 6 @[4 5 6 7 8 9] )
# => 2
# in tuple
(index-of 2 [1 2 3 4])
# => 1