1 multi sub postfix:<❢> (Int $i where $i < 0) is tighter(&infix:<*>) {
 2     fail "Not a Natural Number in Factorial"
 3 }
 4 multi sub postfix:<❢> (Int $i where 0|1) is tighter(&infix:<*>) { 1 }
 5 multi sub postfix:<❢> (Int $i where $i > 1) is tighter(&infix:<*>) {
 6     $i * ($i-1)❢
 7 }
 8 
 9 use Test;
10 isa-ok -1❢, Failure, "Factorial for -1 fails";
11 ok 0❢ == 1, "Factorial for 0";
12 ok 1❢ == 1, "Factorial for 1";
13 ok 5❢ == 120, "Factorial for a larger integer";