code: def picture_view(request, user_id, year=None):
      
      try:
          user = User.objects.get(id=user_id)
      except User.DoesNotExist:
          raise Http404
      default_image_path = os.path.join(settings.PROJECT_ROOT, "static/img/default_profile_pic.png")
  
      if user is None:
          raise Http404
      else:
          if year is None:
              preferred = user.preferred_photo
  
              if preferred is None:
                  data = user.default_photo
                  if data is None:
                      image_buffer = io.open(default_image_path, mode="rb")
                  else:
                      image_buffer = io.BytesIO(data)
  
              # Exclude 'graduate' from names array
              else:
                  data = preferred.binary
                  if data:
                      image_buffer = io.BytesIO(data)
                  else:
                      image_buffer = io.open(default_image_path, mode="rb")
          else:
              grade_number = Grade.number_from_name(year)
              if user.photos.filter(grade_number=grade_number).exists():
                  data = user.photos.filter(grade_number=grade_number).first().binary
              else:
                  data = None
              if data:
                  image_buffer = io.BytesIO(data)
              else:
                  image_buffer = io.open(default_image_path, mode="rb")
  
          response = HttpResponse(content_type="image/jpeg")
          response["Content-Disposition"] = "filename={}_{}.jpg".format(user_id, year or preferred)
          try:
              img = image_buffer.read()
          except UnicodeDecodeError:
              img = io.open(default_image_path, mode="rb").read()
  
          image_buffer.close()
          response.write(img)
  
          return response
docs: Displays a view of a user's picture.
  
      Args:
          user_id
              The ID of the user whose picture is being fetched.
          year
              The user's picture from this year is fetched. If not
              specified, use the preferred picture.