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: serializable_generator.rb
    path of file: ./repos/jsonapi-rails/lib/generators/jsonapi/serializable
    
    the code of the file until where you have to start completion: module Jsonapi
  class Serializ
    
    def copy_serializable_file
      fail "#{class_name} model not found." unless model_exists?

      template 'serializable.rb.erb',
               File.join('app/serializable', class_path,
                         "#{serializable_file_name}.rb")
    end