curl --header "Authorization: key=API_KEY" \
       --header "Content-Type: application/json" \
       https://fcm.googleapis.com/fcm/send \
       -d "{
  "to" : "/topics/global",
  "priority" : "high",
  "notification" : {
    "sound" : "enabled",
    "title" : "curl push!",
    "body" : "it worked!",
  }
}"