tr/M// is sufficient

Indeed it is ... as any golfer would know. :) Speaking of which, note that y is an oddball synonym for tr -- added, not for golfers (because code golf didn't exist back then), but to entice diehard sed devotees to the new frontier of Perl.

I have to give a further honourable mention to y///c -- aka Abigail's length horror -- because it's one character shorter than the prosaic length.

Finally, note that Perl's flexibility of being able to choose your own delimiter has made tr a favourite of obfuscators (and bored golfers) ... as I remember from this amusing expression:

($.|y|||c|y|a|||y|e|||y|i|||y|o|||y|u|||y|y||)||print
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