sub undefined {
    return;
}

sub empty {
    my @array= ();
    return @array;
}

my @undefd;
my @empty= ();
my @dedefd= (1,2,3);
@dedefd= undefined();
my @emptied= (1,2,3);
@emptied= empty();
my @undef2= undefined();
my @empty2= empty();
print "\@undefd is defined\n"   if  defined @undefd;
print "\@empty is defined\n"    if  defined @empty;
print "\@dedefd is defined\n"   if  defined @dedefd;
print "\@emptied is defined\n"  if  defined @emptied;
print "\@undef2 is defined\n"   if  defined @undef2;
print "\@empty2 is defined\n"   if  defined @empty2;