class Roda::RodaPlugins::MiddlewareStack::StackPosition

middleware can be inserted.
Represents a specific position in the application’s middleware stack where new

def initialize(app, middleware, position) 

def initialize(app, middleware, position)
  @app = app
  @middleware = middleware
  @position = position
end

def use(*args, &block)

middleware after earlier middleware, similar to how +Roda.use+ works.
Increments the position so that calling this multiple times adds later
Insert a new middleware into the current position in the middleware stack. 
def use(*args, &block)
  @middleware.insert(@position, [args, block])
  @app.send(:build_rack_app)
  @position += 1
  nil
end