Coverge improvements (#22)

* Update cli.py

* improved tests

* chnages for proper testing

* Type check using isinstance

* Replace elifs with if when used after return

* twitter.com --> www.ibm.com

* fix typo

* test archive urll parser and dunders

* Update test_wrapper.py

waybackpy/wrapper.py

@@ -51,8 +51,7 @@ def _get_response(req):
         try:
             response = urlopen(req)  # nosec
         except Exception as e:
-            exc = WaybackError("Error while retrieving %s" % req.full_ur
-            )
+            exc = WaybackError("Error while retrieving %s" % req.full_url)
             exc.__cause__ = e
             raise exc
     return response