map(1..3, try { [1][5] } catch { # * 10 })                             => [10 20 30], err=<nil>
filter(1..5, try { [1][5] } catch { # > 2 })                           => [3 4 5], err=<nil>
map(1..3, try { failTimes(#) } catch { retry })                        => [100 200 300], err=<nil>
attempts: map[1:3 2:3 3:3]
map(1..2, try { throw("x") } catch e { #index })                       => [0 1], err=<nil>
try { throw("x") } catch index { index.Message }                       => x, err=<nil>
