module Faraday::MiddlewareRegistry

def load_middleware(key)
  value = registered_middleware[key]
  case value
  when Module
    value
  when Symbol, String
    middleware_mutex do
      @registered_middleware[key] = const_get(value)
    end
  when Proc
    middleware_mutex do
      @registered_middleware[key] = value.call
    end
  end
end