why aren't these methods available in rails console?

gistfile1.rb

I'm trying to work with the rails console and this gem:
https://github.com/sethvargo/isbndb

in my my Gem file:

gem 'isbndb', '~> 2.0.2'                                                                                                                                                                                
(ran 'bundle install' and 'bundle update')

opened the console (rails c)

@query = ISBNdb::Query.new #=> #<ISBNdb::Query:0x00000105c18d00> 
@query.class #=> ISBNdb::Query

but, why can't i do:

@query.find_book_by_title('Ruby')

NoMethodError: undefined method `find_book_by_title' for #<ISBNdb::Query:0x00000105c18d00>
        from (irb):28
        from /Users/x/.rvm/gems/ruby-2.0.0-p353/gems/railties-4.0.4/lib/rails/commands/console.rb:90:in `start'
        from /Users/x/.rvm/gems/ruby-2.0.0-p353/gems/railties-4.0.4/lib/rails/commands/console.rb:9:in `start'
        from /Users/x/.rvm/gems/ruby-2.0.0-p353/gems/railties-4.0.4/lib/rails/commands.rb:62:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'
        
        

I will confess that i don't know what this is from the docs:
access_keys:
  - KEY_1
  - KEY_2
  
So i implemented it as:
access_keys:
  _ 'thor'