\w+a Unicode word character, repeated at least once
\[the literal [ (9110 / 1338 / 5B16)
Group name(?P<name>[\w ]+) +matches at least one character from the set below:
\wa Unicode word character
the literal (3210 / 408 / 2016)
\]the literal ] (9310 / 1358 / 5D16)
.*any Unicode character (except for line terminators), repeated any number of times
:the literal : (5810 / 728 / 3A16)
\s+a Unicode whitespace character, repeated at least once
Group help_msg(?P<help_msg>(?:[^\n]|\n(?!\w+\[))*) Non-Capturing Group(?:[^\n]|\n(?!\w+\[))* *repeats the group contents below any number of times:
Negated Character Class[^\n] \na line-feed (newline) character (ASCII 10)
2nd Alternative\n(?!\w+\[) \na line-feed (newline) character (ASCII 10)
Negative Lookahead(?!\w+\[) \w+a Unicode word character, repeated at least once
\[the literal [ (9110 / 1338 / 5B16)
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