Turn in the permutation predicate that you worked on at the end of the Prolog lab in a file called perm.prolog.
Write a factorial predicate to be able to successfully answer the query factorial(6,X). Submit your code in a file called factorial.prolog. Note that adding functionality to work the other way around, e.g. factorial(N,120). is trickier, and something we will do in class after we have covered the Prolog that we will need.