def comment_lines(lines):
ret = []<EOL>for line in lines:<EOL><INDENT>ws_prefix, rest, ignore = RE_LINE_SPLITTER_COMMENT.match(line).groups()<EOL>ret.append(ws_prefix + '<STR_LIT:#>' + rest)<EOL><DEDENT>return '<STR_LIT>'.join(ret)<EOL>
Comment out the given list of lines and return them.  The hash mark will
    be inserted before the first non-whitespace character on each line.