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#!perl -w

...
    'ex_n'  => sub { exists $tran_types{$char_n} },
});

Benchmark: running co_Y, co_nA, co_nZ, co_nl, ex_Y, ex_n, re_Y, re_n, 
+each for at least 15 CPU seconds...
      co_Y: 18 wallclock secs (14.95 usr +  0.05 sys = 15.00 CPU) @ 26
+6935.00/s (n=4004025)
...
co_nl 720798/s  256%  196%  175%  170%  103%    1%    --  -16%
ex_n  862264/s  326%  254%  228%  223%  143%   21%   20%    --