csu3_am335x/EVSE/GPL/libxml2-2.7.6/test/regexp/ranges2

=>(a|b{0,3}){0,1}
a
aa
b
bb
bbb
bbbb
ab
ba
=>([0-9]{0,3}|([0-9]{0}|[0-9]{0,3})){0,3}
0
00
123
abc