prop_param_is_added url = 
  let url' = (addParam ("name", "joe") url) in
    (lookup "name" (url_params url')) == (Just "joe")
  where types = (url :: URL)
prop_param_is_added url = 
  let url' = (addParam ("name", "joe") url) in
    (lookup "name" (url_params url')) == (Just "joe")
  where types = (url :: URL)
prop_param_is_added url = 
  let url' = (addParam ("name", "joe") url) in
    (lookup "name" (url_params url')) == (Just "joe")
  where types = (url :: URL)