module Roda::RodaPlugins::MultiRun::ClassMethods

def run(prefix, app=nil, &block)

removed. It is an error to provide both an app and block in the same call.
a block or an app is provided, any stored route for the prefix is
there is a request for the route to get the app to call. If neither
r.multi_run is called. If a block is given, it is called every time
Add a rack application to dispatch to for the given prefix when 
def run(prefix, app=nil, &block)
  prefix = prefix.to_s
  if app 
    raise Roda::RodaError, "cannot provide both app and block to Roda.run" if block
    opts[:multi_run_apps][prefix] = app
    opts[:multi_run_app_blocks].delete(prefix)
  elsif block
    opts[:multi_run_apps].delete(prefix)
    opts[:multi_run_app_blocks][prefix] = block
  else
    opts[:multi_run_apps].delete(prefix)
    opts[:multi_run_app_blocks].delete(prefix)
  end
  self::RodaRequest.refresh_multi_run_regexp!
end