s/1\B/o/
:
s/\b/ __/
y/1234567890/0123456789/
s/o9/9/
T
s/_0/_/p
T
s# \b#/#
s#_$#/\\@\n#
y/_/ /
:0
s#^ \(.*\)\\$#\1  \\#m
:1
s#^\(/ *\) #\1_#
t1
s/@//
P
/^ /b0
y#/\\_#\\/ #
:2
s#\(\\.*\)  /$# \1/#
:3
s# \( *\\/\)#_\1#
t3
s/\n//
p
/\\\//d
b2