export function __TS__MapGroupBy(
this: void,
items: Iterable,
keySelector: (item: T, index: number) => K
): Map {
const result = new Map();
let i = 0;
for (const item of items) {
const key = keySelector(item, i);
if (result.has(key)) {
result.get(key)!.push(item);
} else {
result.set(key, [item]);
}
i++;
}
return result;
}