# undef if given a list of a single undef. This mimics the
# behaviour of many user-defined subs and built-ins (eg: open) that
# always return undef regardless of context.
+#
+# We also do an 'empty return' if no arguments are passed. This
+# mimics the PBP guideline for returning nothing.
sub list_mirror {
return undef if (@_ == 1 and not defined $_[0]);
+ return if not @_;
return @_;
}