\s*any whitespace character, repeated any number of times
?repeats the group contents below at most once:
"the literal " (3410 / 428 / 2216)
.*?any character (except for line terminators), repeated any number of times
\1the text saved by group 1
\s*any whitespace character, repeated any number of times
Non-Capturing Group(?:,|$) ,the literal , (4410 / 548 / 2C16)
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