code: def extract_access_token(request):
      
      auth_header = request.META.get('HTTP_AUTHORIZATION', '')
  
      if re.compile('^[Bb]earer\s{1}.+$').match(auth_header):
          access_token = auth_header.split()[1]
      else:
          access_token = request.GET.get('access_token', '')
  
      return access_token
docs: Get the access token using Authorization Request Header Field method.
      Or try getting via GET.
      See: http://tools.ietf.org/html/rfc6750#section-2.1
  
      Return a string.