I am familiar with modules giving a class access to instance methods included in the module, but I have not seen modules giving classes access to local variables.

Here is file A:

module SequelPlayground
  class Article
    attr_reader :title, :body, :author_id, :id
    def initialize(attributes)
      @title         = attributes[:title]
      @body          = attributes[:body]
      @author_id = attributes[:author_id]
      @id            = attributes[:id]
    end
    def self.next_id
      table.count + 1
    end
    def self.table
      DB.from(:articles)   #SELECT * FROM articles
    end
  end
end

Here is file B:

module SequelPlayground
  DB = Sequel.postgres("sequel-playground")

  class Server < Sinatra::Base
    get '/' do
      erb :index
    end
  end
end

Why does file A have access to the local variable DB? Are anything within a module in the same namespace even across files?