code: def add_media(dest, media):
      
      if django.VERSION >= (2, 2):
          dest._css_lists += media._css_lists
          dest._js_lists += media._js_lists
      elif django.VERSION >= (2, 0):
          combined = dest + media
          dest._css = combined._css
          dest._js = combined._js
      else:
          dest.add_css(media._css)
          dest.add_js(media._js)
docs: Optimized version of django.forms.Media.__add__() that doesn't create new objects.