open Nat

#eval   gcd 8 12
#reduce gcd 8 12

#eval   gcd 0 9
#reduce gcd 0 9

#eval   gcd 4 0
#reduce gcd 4 0

#eval   gcd 1 10
#reduce gcd 1 10

#eval gcd (2*3*7*11*17) (2*7*23)
#eval gcd (2*7*23) (2*3*7*11*17)