## When we are looking on REGEXP for something that is after other,
## genreally "\n", we forget about the beggin of the string,
## that enables an occurrence that is not after "\n".
## Soo, to do this in only one REGEXP we use (?:^|\n)

  ## remove comments:
  $str =~ s/(?:^|\n)[ \t]*#//gs

##</code><code>##

  $str =~ s/^[ \t]*#.*\n//gm;