function
(in ds key &opt dflt)
Get value in ds at key, works on associative data structures. Arrays,
tuples, tables, structs, strings, symbols, and buffers are all
associative and can be used. Arrays, tuples, strings, buffers, and
symbols must use integer keys that are in bounds or an error is raised.
Structs and tables can take any value as a key except nil and will
return nil or dflt if not found.
(get [4 5 6] -1 ) # => nil
(in [4 5 6] -1 42 ) # error
(get-in [4 5 6] [-1] 42 ) # => 42
(get {:a 1} -1 ) # => nil
(in {:a 1} -1 42 ) # => 42
(get-in {:a 1} [-1] 42 ) # => 42(in [10 11 12 13] 0 42 ) # => 10
(in {:a 10 :b 20} :a 42 ) # => 10
(in [10 11 12] 99 42 ) # error
(in [10 11 12] -1 42 ) # error
(in [10 11 12] -2 42 ) # error
(in {:a 1} :z 42 ) # => 42
(map (fn [x] (in x 0 42)) [ 'a :a "a" [97] @[97] {0 97} @{0 97} {:a 1} ])
# => @[ 97 97 97 97 97 97 97 42 ]