We expose the data
Riot's API doesn't.

// 1. Get PUUIDs for 10 players
const puuids = await getPuuids(players);

// 2. Fetch matchlists for each player
const matchLists = await Promise.all(
  puuids.map(p => api.get('/lol/match/v5/matches/by-puuid/...'))
);

// 3. Find intersection of match IDs
const commonMatches = intersect(matchLists);

// 4. Fetch full match details (Rate Limit Nightmare)
const matches = [];
for (const matchId of commonMatches) {
  // Wait to respect 20 req/s limit...
  await sleep(100); 
  const match = await api.get(`/lol/match/v5/matches/${matchId}`);
  matches.push(match);
}

// 5. Parse timelines for gold diff
const timelines = await fetchTimelines(matches);
const goldDiffs = calculateGoldDiff(timelines);