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: classifications_controller.rb
    path of file: ./repos/solidus/api/app/controllers/spree/api
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Spree
  module Api
    class ClassificationsController < Spree::Api::BaseController
      def update
        authorize! :update, Product
        authorize! :update, Taxon
        classif
    
      def update
        authorize! :update, Product
        authorize! :update, Taxon
        classification = Spree::Classification.find_by(
          product_id: params[:product_id],
          taxon_id: params[:taxon_id]
        )
        # Because position we get back is 0-indexed.
        # acts_as_list is 1-indexed.
        classification.insert_at(params[:position].to_i + 1)
        head :ok
      end