module Rackup::Handler

def self.default
  if rack_handler = ENV[RACKUP_HANDLER]
    self.get(rack_handler)
  elsif rack_handler = ENV[RACK_HANDLER]
    warn "RACK_HANDLER is deprecated, use RACKUP_HANDLER."
    self.get(rack_handler)
  else
    pick SERVER_NAMES
  end
end