^start of line
\s*any whitespace character, repeated any number of times
#the literal # (3510 / 438 / 2316)
.*any character (except for line terminators), 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