src/vs/workbench/api/common/extHostTypes.ts/Location/constructor
class Location:	constructor(uri: URI, rangeOrPosition: Range | Position) {
		this.uri = uri;

		if (!rangeOrPosition) {
			//that's OK
		} else if (Range.isRange(rangeOrPosition)) {
			this.range = Range.of(rangeOrPosition);
		} else if (Position.isPosition(rangeOrPosition)) {
			this.range = new Range(rangeOrPosition, rangeOrPosition);
		} else {
			throw new Error('Illegal argument');
		}
	}