1declare namespace Intl {
2  interface NumberRangeFormatPart extends NumberFormatPart {
3    source: "startRange" | "endRange" | "shared"
4  }
5
6  interface NumberFormat {
7    formatRange(start: number | bigint, end: number | bigint): string;
8    formatRangeToParts(start: number | bigint, end: number | bigint): NumberRangeFormatPart[];
9  }
10}
11