title: If-else statement on haar cascade application
body: <p>I have the following code:</p>
  
  <pre><code>import numpy as np
  import cv2
  
  face_cascade = cv2.CascadeClassifier('D:/haarcascade_frontalface_default.xml')
  eye_cascade = cv2.CascadeClassifier('D:/haarcascade_eye.xml')
  
  img = cv2.imread('D:/lena.jpg')
  gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
  faces = face_cascade.detectMultiScale(gray, 1.3, 5)
  for (x,y,w,h) in faces:
      cv2.rectangle(img,(x,y),(x+w,y+h),(255,170,0),2)
      roi_gray = gray[y:y+h, x:x+w]
      roi_color = img[y:y+h, x:x+w]
      eyes = eye_cascade.detectMultiScale(roi_gray)
      for (ex,ey,ew,eh) in eyes:
          cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,255,100),2)
  
  cv2.imshow('img',img)
  cv2.waitKey(0)
  cv2.destroyAllWindows()
  </code></pre>
  
  <p>It currently works great. I now want to add an if-else statement to take a costume action if a face is detected or not. Where would I place that statement, and what parameter would I have to use?</p>