Does not redis_orm support HABTM?

I created 2 models

class User < RedisOrm::Base
  property :name, String

  has_many :books
end

class Book < RedisOrm::Base
  property :title, String

  has_many :users, as: :authors
end

And

user = User.create(name: 'Kent Beck')
user.books << Book.create(title: 'Refactoring')

But this code fails as follows:

       undefined method `pluralize' for :authors:Symbol

How should I do in this case? has_many looks like not support HABTM https://github.com/german/redis_orm/blob/master/lib/redis_orm/associations/has_many.rb#L7

german / redis_orm

Does not redis_orm support HABTM? #5