/usr/share/doc/m4/examples/hanoi.m4 is in m4 1.4.18-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | divert(-1)
# move(from, to)
define(`move', `Move one disk from `$1' to `$2'.
')
# _hanoi (cnt, from, to, aux)
define(`_hanoi', `ifelse(eval(`$1'<=1), 1, `move($2, $3)',
`$0(decr($1), $2, $4, $3)move($2, $3)$0(decr($1), $4, $3, $2)')')
# hanoi (cnt)
define(`hanoi', `_$0(`$1', source, destination, auxilliary)')
# traceon(`move', `_hanoi', `decr')
divert`'dnl
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