class Roda::RodaPlugins::MiddlewareStack::Stack

def before(&block)

new middleware at the end of the stack.
It the block never returns true, returns a StackPosition that will insert
given, but not the middleware block.
the block returns true. Yields the middleware and any middleware arguments
Return a StackPosition representing the position before the middleware where 
def before(&block)
  handle(0, &block)
end