/**
 * In probability theory and statistics, the Poisson distribution
 * (/ˈpwɑːsɒn/; French pronunciation: [pwasɔ̃]), named after
 * French mathematician Siméon Denis Poisson,
 * is a discrete probability distribution that expresses the
 * probability of a given number of events occurring in a fixed
 * interval of time or space if these events occur with a
 * known constant mean rate and independently of the time since the last event.
 * @param lambda rate
 */
export declare const poisson: (lambda: number) => number;