initial commit: scaffolding

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diff --git a/node_modules/rxjs/src/internal/observable/iif.ts b/node_modules/rxjs/src/internal/observable/iif.ts
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+import { Observable } from '../Observable';
+import { defer } from './defer';
+import { ObservableInput } from '../types';
+
+/**
+ * Checks a boolean at subscription time, and chooses between one of two observable sources
+ *
+ * `iif` expects a function that returns a boolean (the `condition` function), and two sources,
+ * the `trueResult` and the `falseResult`, and returns an Observable.
+ *
+ * At the moment of subscription, the `condition` function is called. If the result is `true`, the
+ * subscription will be to the source passed as the `trueResult`, otherwise, the subscription will be
+ * to the source passed as the `falseResult`.
+ *
+ * If you need to check more than two options to choose between more than one observable, have a look at the {@link defer} creation method.
+ *
+ * ## Examples
+ *
+ * Change at runtime which Observable will be subscribed
+ *
+ * ```ts
+ * import { iif, of } from 'rxjs';
+ *
+ * let subscribeToFirst;
+ * const firstOrSecond = iif(
+ *   () => subscribeToFirst,
+ *   of('first'),
+ *   of('second')
+ * );
+ *
+ * subscribeToFirst = true;
+ * firstOrSecond.subscribe(value => console.log(value));
+ *
+ * // Logs:
+ * // 'first'
+ *
+ * subscribeToFirst = false;
+ * firstOrSecond.subscribe(value => console.log(value));
+ *
+ * // Logs:
+ * // 'second'
+ * ```
+ *
+ * Control access to an Observable
+ *
+ * ```ts
+ * import { iif, of, EMPTY } from 'rxjs';
+ *
+ * let accessGranted;
+ * const observableIfYouHaveAccess = iif(
+ *   () => accessGranted,
+ *   of('It seems you have an access...'),
+ *   EMPTY
+ * );
+ *
+ * accessGranted = true;
+ * observableIfYouHaveAccess.subscribe({
+ *   next: value => console.log(value),
+ *   complete: () => console.log('The end')
+ * });
+ *
+ * // Logs:
+ * // 'It seems you have an access...'
+ * // 'The end'
+ *
+ * accessGranted = false;
+ * observableIfYouHaveAccess.subscribe({
+ *   next: value => console.log(value),
+ *   complete: () => console.log('The end')
+ * });
+ *
+ * // Logs:
+ * // 'The end'
+ * ```
+ *
+ * @see {@link defer}
+ *
+ * @param condition Condition which Observable should be chosen.
+ * @param trueResult An Observable that will be subscribed if condition is true.
+ * @param falseResult An Observable that will be subscribed if condition is false.
+ * @return An observable that proxies to `trueResult` or `falseResult`, depending on the result of the `condition` function.
+ */
+export function iif<T, F>(condition: () => boolean, trueResult: ObservableInput<T>, falseResult: ObservableInput<F>): Observable<T | F> {
+  return defer(() => (condition() ? trueResult : falseResult));
+}