Debugging prints
# Scalar:
print STDERR "Debug: '$a'\n";
# Array:
print STDERR "Debug: @a\n";
print STDERR "Debug: ", join "|", @a, "\n";
# Hash:
print STDERR "Debug: ", join "|", %h, "\n";
print STDERR "Debug: ";
foreach (keys %h) { print STDERR "$_=>$h{$_}|";
print STDERR "\n";
print STDERR "Debug: ";
print STDERR "$_=>$h{$_}|" for keys %h;
print STDERR "\n";