my $di = do $_ or die "Error reading digraphs file $_: ", $@ || $!;
while (my ($mnem, $cp) = each %$di) {
length $mnem == 2 or next; # limit to digraphs
my $di = do $_ or die "Error reading digraphs file $_: ", $@ || $!;
while (my ($mnem, $cp) = each %$di) {
length $mnem == 2 or next; # limit to digraphs