It's time for a moustache

Let's overlay a moustache on top:

import cv2 
import numpy as np 

mouth_cascade = cv2.CascadeClassifier('./cascade_files/haarcascade_mcs_mouth.xml') 

moustache_mask = cv2.imread('./images/moustache.png')
h_mask, w_mask = moustache_mask.shape[:2] 

if mouth_cascade.empty(): 
  raise IOError('Unable to load the mouth cascade classifier xml file') 

cap = cv2.VideoCapture(0) 
scaling_factor = 0.5 

while True: 
    ret, frame = cap.read() 
    frame = cv2.resize(frame, None, fx=scaling_factor, fy=scaling_factor, interpolation=cv2.INTER_AREA) 
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) 

    mouth_rects = mouth_cascade.detectMultiScale(gray, 1.3, 5) 
    if len(mouth_rects) > 0: 
        (x,y,w,h) = mouth_rects[0] 
        h, w = int(0.6*h), int(1.2*w) 
        x -= int(0.05*w)
        y -= int(0.55*h)
        frame_roi = frame[y:y+h, x:x+w] 
        moustache_mask_small = cv2.resize(moustache_mask, (w, h), interpolation=cv2.INTER_AREA) 

        gray_mask...