public boolean checkIfUsernameExists(String username, DataSnapshot datasnapshot) {
        Log.d(TAG, "checkIfUsernameExists: check if " + username + "already exists.");

        User user = new User();

        for (DataSnapshot ds: datasnapshot.getChildren()) {
            Log.d(TAG, "checkIfUsernameExists: datasnapshot: " + ds);

            user.setUsername(ds.getValue(User.class).getUsername());
            Log.d(TAG, "checkIfUsernameExists: username: " + user.getUsername());

            if(StringManipulation.expandUsername(user.getUsername()).equals(username)) {
                Log.d(TAG, "checkIfUsernameExists: FOUND A MATCH: " + user.getUsername());

                return true;
            }
        }
        return false;
    }