from typing import Optional
from typing import Set
import re


def extract_requested_tags(comment: str) -> Optional[Set[str]]:
    """
    Returns the set of test tags requested in the comment.
    """
    for line in comment.splitlines():
        match = re.fullmatch(r'/test ([\w,\- ]+)', line)
        if match is not None:
            return set([x.strip() for x in match.group(1).split(',')])
    return None