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: model.rb
    path of file: ./repos/mixed_gauge/lib/mixed_gauge
    
    the code of the file until where you have to start completion: require 'active_support/concern'

module MixedGauge
  # @example
  #   class User < ActiveRecord::Base
  #     include MixedGauge::Model
  #     use_cluster :user
  #     def
    
      def put!(attributes)
        raise '`distkey` is not defined. Use `def_distkey`.' unless distkey
        @before_put_callback.call(attributes) if @before_put_callback

        if (key = attributes[distkey]) || attributes[distkey.to_s]
          shard_for(key).create!(attributes)
        else
          raise MixedGauge::MissingDistkeyAttribute
        end