initial commit: scaffolding

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diff --git a/node_modules/rxjs/src/internal/observable/forkJoin.ts b/node_modules/rxjs/src/internal/observable/forkJoin.ts
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+import { Observable } from '../Observable';
+import { ObservedValueOf, ObservableInputTuple, ObservableInput } from '../types';
+import { argsArgArrayOrObject } from '../util/argsArgArrayOrObject';
+import { innerFrom } from './innerFrom';
+import { popResultSelector } from '../util/args';
+import { createOperatorSubscriber } from '../operators/OperatorSubscriber';
+import { mapOneOrManyArgs } from '../util/mapOneOrManyArgs';
+import { createObject } from '../util/createObject';
+import { AnyCatcher } from '../AnyCatcher';
+
+// forkJoin(any)
+// We put this first because we need to catch cases where the user has supplied
+// _exactly `any`_ as the argument. Since `any` literally matches _anything_,
+// we don't want it to randomly hit one of the other type signatures below,
+// as we have no idea at build-time what type we should be returning when given an any.
+
+/**
+ * You have passed `any` here, we can't figure out if it is
+ * an array or an object, so you're getting `unknown`. Use better types.
+ * @param arg Something typed as `any`
+ */
+export function forkJoin<T extends AnyCatcher>(arg: T): Observable<unknown>;
+
+// forkJoin(null | undefined)
+export function forkJoin(scheduler: null | undefined): Observable<never>;
+
+// forkJoin([a, b, c])
+export function forkJoin(sources: readonly []): Observable<never>;
+export function forkJoin<A extends readonly unknown[]>(sources: readonly [...ObservableInputTuple<A>]): Observable<A>;
+export function forkJoin<A extends readonly unknown[], R>(
+  sources: readonly [...ObservableInputTuple<A>],
+  resultSelector: (...values: A) => R
+): Observable<R>;
+
+// forkJoin(a, b, c)
+/** @deprecated Pass an array of sources instead. The rest-parameters signature will be removed in v8. Details: https://rxjs.dev/deprecations/array-argument */
+export function forkJoin<A extends readonly unknown[]>(...sources: [...ObservableInputTuple<A>]): Observable<A>;
+/** @deprecated Pass an array of sources instead. The rest-parameters signature will be removed in v8. Details: https://rxjs.dev/deprecations/array-argument */
+export function forkJoin<A extends readonly unknown[], R>(
+  ...sourcesAndResultSelector: [...ObservableInputTuple<A>, (...values: A) => R]
+): Observable<R>;
+
+// forkJoin({a, b, c})
+export function forkJoin(sourcesObject: { [K in any]: never }): Observable<never>;
+export function forkJoin<T extends Record<string, ObservableInput<any>>>(
+  sourcesObject: T
+): Observable<{ [K in keyof T]: ObservedValueOf<T[K]> }>;
+
+/**
+ * Accepts an `Array` of {@link ObservableInput} or a dictionary `Object` of {@link ObservableInput} and returns
+ * an {@link Observable} that emits either an array of values in the exact same order as the passed array,
+ * or a dictionary of values in the same shape as the passed dictionary.
+ *
+ * <span class="informal">Wait for Observables to complete and then combine last values they emitted;
+ * complete immediately if an empty array is passed.</span>
+ *
+ * ![](forkJoin.png)
+ *
+ * `forkJoin` is an operator that takes any number of input observables which can be passed either as an array
+ * or a dictionary of input observables. If no input observables are provided (e.g. an empty array is passed),
+ * then the resulting stream will complete immediately.
+ *
+ * `forkJoin` will wait for all passed observables to emit and complete and then it will emit an array or an object with last
+ * values from corresponding observables.
+ *
+ * If you pass an array of `n` observables to the operator, then the resulting
+ * array will have `n` values, where the first value is the last one emitted by the first observable,
+ * second value is the last one emitted by the second observable and so on.
+ *
+ * If you pass a dictionary of observables to the operator, then the resulting
+ * objects will have the same keys as the dictionary passed, with their last values they have emitted
+ * located at the corresponding key.
+ *
+ * That means `forkJoin` will not emit more than once and it will complete after that. If you need to emit combined
+ * values not only at the end of the lifecycle of passed observables, but also throughout it, try out {@link combineLatest}
+ * or {@link zip} instead.
+ *
+ * In order for the resulting array to have the same length as the number of input observables, whenever any of
+ * the given observables completes without emitting any value, `forkJoin` will complete at that moment as well
+ * and it will not emit anything either, even if it already has some last values from other observables.
+ * Conversely, if there is an observable that never completes, `forkJoin` will never complete either,
+ * unless at any point some other observable completes without emitting a value, which brings us back to
+ * the previous case. Overall, in order for `forkJoin` to emit a value, all given observables
+ * have to emit something at least once and complete.
+ *
+ * If any given observable errors at some point, `forkJoin` will error as well and immediately unsubscribe
+ * from the other observables.
+ *
+ * Optionally `forkJoin` accepts a `resultSelector` function, that will be called with values which normally
+ * would land in the emitted array. Whatever is returned by the `resultSelector`, will appear in the output
+ * observable instead. This means that the default `resultSelector` can be thought of as a function that takes
+ * all its arguments and puts them into an array. Note that the `resultSelector` will be called only
+ * when `forkJoin` is supposed to emit a result.
+ *
+ * ## Examples
+ *
+ * Use `forkJoin` with a dictionary of observable inputs
+ *
+ * ```ts
+ * import { forkJoin, of, timer } from 'rxjs';
+ *
+ * const observable = forkJoin({
+ *   foo: of(1, 2, 3, 4),
+ *   bar: Promise.resolve(8),
+ *   baz: timer(4000)
+ * });
+ * observable.subscribe({
+ *  next: value => console.log(value),
+ *  complete: () => console.log('This is how it ends!'),
+ * });
+ *
+ * // Logs:
+ * // { foo: 4, bar: 8, baz: 0 } after 4 seconds
+ * // 'This is how it ends!' immediately after
+ * ```
+ *
+ * Use `forkJoin` with an array of observable inputs
+ *
+ * ```ts
+ * import { forkJoin, of, timer } from 'rxjs';
+ *
+ * const observable = forkJoin([
+ *   of(1, 2, 3, 4),
+ *   Promise.resolve(8),
+ *   timer(4000)
+ * ]);
+ * observable.subscribe({
+ *  next: value => console.log(value),
+ *  complete: () => console.log('This is how it ends!'),
+ * });
+ *
+ * // Logs:
+ * // [4, 8, 0] after 4 seconds
+ * // 'This is how it ends!' immediately after
+ * ```
+ *
+ * @see {@link combineLatest}
+ * @see {@link zip}
+ *
+ * @param args Any number of `ObservableInput`s provided either as an array, as an object
+ * or as arguments passed directly to the operator.
+ * @return Observable emitting either an array of last values emitted by passed Observables
+ * or value from project function.
+ */
+export function forkJoin(...args: any[]): Observable<any> {
+  const resultSelector = popResultSelector(args);
+  const { args: sources, keys } = argsArgArrayOrObject(args);
+  const result = new Observable((subscriber) => {
+    const { length } = sources;
+    if (!length) {
+      subscriber.complete();
+      return;
+    }
+    const values = new Array(length);
+    let remainingCompletions = length;
+    let remainingEmissions = length;
+    for (let sourceIndex = 0; sourceIndex < length; sourceIndex++) {
+      let hasValue = false;
+      innerFrom(sources[sourceIndex]).subscribe(
+        createOperatorSubscriber(
+          subscriber,
+          (value) => {
+            if (!hasValue) {
+              hasValue = true;
+              remainingEmissions--;
+            }
+            values[sourceIndex] = value;
+          },
+          () => remainingCompletions--,
+          undefined,
+          () => {
+            if (!remainingCompletions || !hasValue) {
+              if (!remainingEmissions) {
+                subscriber.next(keys ? createObject(keys, values) : values);
+              }
+              subscriber.complete();
+            }
+          }
+        )
+      );
+    }
+  });
+  return resultSelector ? result.pipe(mapOneOrManyArgs(resultSelector)) : result;
+}