You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: registrations_controller.rb
    path of file: ./repos/texterify/app/controllers/api/v1
    
    the code of the file until where you have to start completion: class Api::V1::RegistrationsController < DeviseTokenAuth::RegistrationsController
  before_action :check_if_user_can_sign_up, only: [:create]

  def create
  
    
  def create
    super do |user|
      # The first user that registers is the superadmin user of the instance.
      unless User.exists?(is_superadmin: true)
        user.is_superadmin = true
        user.save!
      end
    end