def METHOD_NAME(self, request, pk):
    """Follow or unfollow a body {?action}=0,1"""
    body = self.get_body(pk)
    # Get query param
    value = request.GET.get("action")
    if value is None:
        return Response({"message": "{?action} is required"}, status=400)
    # Check possible actions
    if value == "0":
        request.user.profile.followed_bodies.remove(body)
    elif value == "1":
        request.user.profile.followed_bodies.add(body)
    else:
        return Response({"message": "Invalid Action"}, status=400)
    return Response(status=204)