^start of line
Positive Lookahead(?=(..)*$) *repeats the group contents below any number of times:
.any character (except for line terminators)
.any character (except for line terminators)
$end of line
a*the literal a (9710 / 1418 / 6116) (case sensitive), repeated any number of times
b*the literal b (9810 / 1428 / 6216) (case sensitive), repeated any number of times
c*the literal c (9910 / 1438 / 6316) (case sensitive), repeated any number of times
$end of line
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string