Ewebmachine.Plug.Run (ewebmachine v2.3.3)
View Source  Plug passing your conn through the HTTP decision
  tree to fill its status and response.
  This plug does not send the HTTP result, instead the conn
  result of this plug must be sent with the plug
  Ewebmachine.Plug.Send. This is useful to customize the Ewebmachine result
  after the run, for instance to customize the error body (void by default).
- Decisions are make according to handlers set in 
conn.private[:resource_handlers](%{handler_name: handler_module}) wherehandler_nameis one of the handler function ofEwebmachine.Handlersandhandler_moduleis the module implementing it. - Initial user state (second parameter of handler function) is
taken from 
conn.private[:machine_init] 
  Ewebmachine.Builder.Handlers :add_handler plug allows you to
  set these parameters in order to use this Plug.
A successfull run will reset the resource handlers and initial state.