```ruby
# frozen_string_literal: true

require 'dynamoid'
require 'dynamoid/tasks/database'

namespace :dynamoid do
  desc 'Creates DynamoDB tables, one for each of your Dynamoid models - does not modify pre-existing tables'
  task create_tables: :environment do
    # Load models so Dynamoid will be able to discover tables expected.
    Dir[File.join(Dynamoid::Config.models_dir, '*.rb')].sort.each { |file| require file }
    if Dynamoid.included_models.any?
      tables = Dynamoid::Tasks::Database.create_tables
      result = tables[:created].map { |c| "#{c} created" } + tables[:existing].map { |e| "#{e} already exists" }
      result.sort.each { |r| puts r }
    else
      puts 'Dynamoid models are not loaded, or you have no Dynamoid models.'
    end
  end

  desc 'Tests if the DynamoDB instance can be contacted using your configuration'
  task ping: :environment do
    success = false
    failure_reason = nil

    begin
      Dynamoid::Tasks::Database.ping
      success = true
    rescue StandardError => e
      failure_reason = e.message
    end

    msg = "Connection to DynamoDB #{success ? 'OK' : 'FAILED'}"
    msg << if Dynamoid.config.endpoint
             " at local endpoint '#{Dynamoid.config.endpoint}'"
           else
             ' at remote AWS endpoint'
           end
    msg << ", reason being '#{failure_reason}'" unless success
    puts msg
  end
end
```

Fix `create_tables` rake task - support nested directories for `model_dir`
user
```ruby
# frozen_string_literal: true

require 'dynamoid'
require 'dynamoid/tasks/database'

namespace :dynamoid do
  desc 'Creates DynamoDB tables, one for each of your Dynamoid models - does not modify pre-existing tables'
  task create_tables: :environment do
    # Load models so Dynamoid will be able to discover tables expected.
    Dir[File.join(Dynamoid::Config.models_dir, '**/*.rb')].sort.each { |file| require file }
    if Dynamoid.included_models.any?
      tables = Dynamoid::Tasks::Database.create_tables
      result = tables[:created].map { |c| "#{c} created" } + tables[:existing].map { |e| "#{e} already exists" }
      result.sort.each { |r| puts r }
    else
      puts 'Dynamoid models are not loaded, or you have no Dynamoid models.'
    end
  end

  desc 'Tests if the DynamoDB instance can be contacted using your configuration'
  task ping: :environment do
    success = false
    failure_reason = nil

    begin
      Dynamoid::Tasks::Database.ping
      success = true
    rescue StandardError => e
      failure_reason = e.message
    end

    msg = "Connection to DynamoDB #{success ? 'OK' : 'FAILED'}"
    msg << if Dynamoid.config.endpoint
             " at local endpoint '#{Dynamoid.config.endpoint}'"
           else
             ' at remote AWS endpoint'
           end
    msg << ", reason being '#{failure_reason}'" unless success
    puts msg
  end
end
```
assistant