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: 20211201171813_create_chat_reactions.rb
    path of file: ./repos/discourse/plugins/chat/db/migrate
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
class CreateChatReactions < ActiveRecord::Migration[6.1]
  def change
    create_table :chat_message_reactions do |t|
      t.integer :cha
    
  def change
    create_table :chat_message_reactions do |t|
      t.integer :chat_message_id
      t.integer :user_id
      t.string :emoji
      t.timestamps
    end

    add_index :chat_message_reactions,
              %i[chat_message_id user_id emoji],
              unique: true,
              name: :chat_message_reactions_index
  end