anchor.diff:  a particular class for documentation purposes.
   Use `Workflow::create_workflow_diagram(class)` in your rake task like:
   
  -    namespace :doc do
  -      desc "Generate a workflow graph for a model passed e.g. as 'MODEL=Order'."
  -      task :workflow => :environment do
  -        require 'workflow/draw'
  -        Workflow::Draw::workflow_diagram(ENV['MODEL'].constantize)
  -      end
  -    end
  -
  +```rb
  +namespace :doc do
  +  desc "Generate a workflow graph for a model passed e.g. as 'MODEL=Order'."
  +  task :workflow => :environment do
  +    require 'workflow/draw'
  +    Workflow::Draw::workflow_diagram(ENV['MODEL'].constantize)
  +  end
  +end
  +```
   
   
   Changelog
  
positive.code: Workflow::TransitionHalted exception. You can provide an additional
  `halted_because` parameter.
  
      def reject(reason)
        halt! 'We do not reject articles unless the reason is important' \
          unless reason =~ /important/i
      end
  
  The traditional `halt` (without the exclamation mark) is still supported
  too. This just prevents the state change without raising an
  
negative.code: here. But the implementation would look similar for the popular
  couchrest library.
  
  ```rb
  require 'couchtiny'
  require 'couchtiny/document'
  require 'workflow'
  
  class User < CouchTiny::Document
    include Workflow
    workflow do
      state :submitted do
        event :activate_via_link, :transitions_to => :proved_email
      end
      state :proved_email
    end
  
    def load_workflow_state
      self[:workflow_state]
    end
  
    def persist_workflow_state(new_value)
      self[:workflow_state] = new_value
      save!
    end
  end
  ```
  
  Please also have a look at
  http://github.com/geekq/workflow/blob/develop/test/couchtiny_example.rb[the full source code].
  