checkers pattern by emoken

:
s/\([^0-9]\|^\)0/\1/
/[0-9]/!b1
h
y/0123456789/9012345678/
x
G
s/\([^0-9]*[0-9]*\)[1-9]0*\(.*\)\n[^0-9]*[0-9]*\([0-8]9*\).*/\1\3a\2/
b
:1
s/a*$/\U&/
s/AA/AB/g
y/AB/10/
h
s/ .*//
x
s/a* //
x
:2
s/a//
G
x
y/01/10/
x
/a/b2
s/.\B/& /g
s/ *\n//

Note that non-ascii characters in the above source code will be escaped (such as \x9f).

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