/**
 * @packageDocumentation
 * @module Number
 */
import { Observable, Subscribable } from 'rxjs';
/**
 * Returns an Observable that emits numbers as a type-safe number generator from a source, if no source is passed it
 * will generate an infinite sequence of positive numbers starting from 0
 *
 * @category Create
 *
 * @param input Optional number source to emit from
 *
 * @example
 * Return an Observable that emits numbers from an Array and multiply by `2`
 * ```ts
 * fromNumber([1, 2, 3, 4]).pipe(mul(2)).subscribe();
 * ```
 * Output: `2, 4, 6, 8`
 *
 * @example
 * Returns an Observable of numbers and take the first 1000, and reduce to an array
 * ```ts
 * fromNumber().pipe(take(1000), reduce((acc, val) => [...acc, val], [])).subscribe();
 * ```
 * Output: `[0, 1, 2, 3, 4, ...]`
 *
 * @returns Observable that emits numbers passed from arguments or array
 */
export declare function fromNumber<T extends number>(input?: Subscribable<Iterable<T> | T> | Iterable<T> | T): Observable<number>;