added missing interfaces

src/classes/FaceDetection.ts

-import { IDimensions, ObjectDetection, Rect } from 'tfjs-image-recognition-base';
+import { Box, IDimensions, ObjectDetection, Rect } from 'tfjs-image-recognition-base';
 
-export class FaceDetection extends ObjectDetection {
+export interface IFaceDetecion {
+  score: number
+  box: Box
+}
+
+export class FaceDetection extends ObjectDetection implements IFaceDetecion {
   constructor(
     score: number,
     relativeBox: Rect,

src/classes/FaceLandmarks.ts

@@ -7,7 +7,12 @@ const relX = 0.5
 const relY = 0.43
 const relScale = 0.45
 
-export class FaceLandmarks {
+export interface IFaceLandmarks {
+  positions: Point[]
+  shift: Point
+}
+
+export class FaceLandmarks implements IFaceLandmarks {
   protected _shift: Point
   protected _positions: Point[]
   protected _imgDims: Dimensions

src/classes/FaceMatch.ts

 import { round } from 'tfjs-image-recognition-base';
 
-export class FaceMatch {
+export interface IFaceMatch {
+  label: string
+  distance: number
+}
+
+export class FaceMatch implements IFaceMatch {
   private _label: string
   private _distance: number