exports.handler = functions.firestore.document('/Polls/{pollId}/followers/{followerId}').onCreate((data, context) => {

  const followerId = data.data().follower_id;
  const userId = admin.firestore().doc(`Polls/${context.params.pollId}`/{user_id:doc.data().user_id});

  //iterate through all collections under "Polls"
  const parentRef = admin.database().ref("Polls");
    return parentRef.once('value').then(snapshot => {
        const updates = {};
        snapshot.forEach(function(child) {
         //if the collection has user_ID field == the user id of the the wildcard pollId, add the follwerId the
            if (child.pollid.userId == userId){
                //write that user ID to the "followers" subcollection of that node
            }
        });
        return parentRef.update(updates);
    });

});