more work with functions

cli/functions.pl

@@ -3,8 +3,8 @@ use strict;
 use warnings;
 
 sub print_error_message {
-    my $message  = shift;
-    print STDOUT "ERROR: " . $message . "\n";
+    my ($message) = @_;
+    print STDOUT "ERROR: " . $message . "!!!\n";
 }
 
 
@@ -13,5 +13,42 @@ print_error_message("something really horrible happened");
 print_error_message("something sort of annoying happened");
 
 
+sub add_two_numbers {
+    my ($x, $y) = @_;
+    my $sum = $x + $y;
+    return $sum;
+}
+
+print add_two_numbers(3, 4) . "\n";
+print add_two_numbers(5, 6) . "\n";
+print add_two_numbers(7, 8) . "\n";
+
+
+sub add_two_numbers_and_mult_by_three {
+    my ($x, $y) = @_;
+    my $sum = add_two_numbers($x, $y);
+    my $sum_times_three = $sum * 3;
+    return $sum_times_three;
+}
+
+print add_two_numbers_and_mult_by_three(3, 4) . "\n";
+print add_two_numbers_and_mult_by_three(5, 6) . "\n";
+print add_two_numbers_and_mult_by_three(7, 8) . "\n";
+
+
+sub factorial {
+    my ($num) = @_;
+    if ($num == 1) {
+        return 1;
+    } else {
+        return $num * factorial($num - 1);
+    }
+}
+
+foreach my $n (1 .. 10) {
+    print factorial($n) . "\n";
+}
+
+
 1;
 __END__