def h (x : Nat) : IO Unit := do
if x == 0  then IO.println "arg is 0"
if x == 1  then IO.println "arg is 1"
if x == 2  then IO.println "arg is 2"
if x == 3  then IO.println "arg is 3"
if x == 4  then IO.println "arg is 4"
if x == 5  then IO.println "arg is 5"
if x == 6  then IO.println "arg is 6"
if x == 7  then IO.println "arg is 7"
if x == 8  then IO.println "arg is 8"
if x == 9  then IO.println "arg is 9"
if x == 10 then IO.println "arg is 10"
if x == 11 then IO.println "arg is 11"
if x == 12 then IO.println "arg is 12"
if x == 13 then IO.println "arg is 13"
if x == 14 then IO.println "arg is 14"
if x == 15 then IO.println "arg is 15"
if x == 16 then IO.println "arg is 16"
if x == 17 then IO.println "arg is 17"
if x == 18 then IO.println "arg is 18"
if x == 19 then IO.println "arg is 19"
if x == 20 then IO.println "arg is 20"