mergeMap

Signature - source.ts#L2120

var mergeMap: <T, U>(
    transform: (value: T, index: number) => Source<U>,
    maxConcurrent?: number | undefined,
) => Operator<T, U>1 var mergeMap: <T, U>(
2     transform: (value: T, index: number) => Source<U>,
3     maxConcurrent?: number | undefined,
4 ) => Operator<T, U>

1	var mergeMap: <T, U>(
2	transform: (value: T, index: number) => Source<U>,
3	maxConcurrent?: number \| undefined,
4	) => Operator<T, U>