basic challenge done

Signed-off-by: Jan Heise <heise@dresearch.de>

challenge.py

@@ -3,11 +3,29 @@
 class Adapter():
     """ Adapter class
 
-    Aufgabe: Asynchron Daten lesen, konvertieren und zurückliefern.
+    Aufgabe: Asynchron XML-Daten lesen, konvertieren und zurückliefern.
     """
 
     def __init__(self, path):
         self.path = path
 
-    def retrieve_json(self, name):
-        pass
+    def retrieve_token(self, name):
+        """
+            Retrieve the content from file name.xml in adapters path directory
+            in a synchronous way, extract the DataReceived/Token and return it
+            as a JSON-Object (stringified) '{"token": value}'.
+        """
+        raise NotImplementedError
+
+    def retrieve_token_async(self, name):
+        """
+            Retrieve the content from file name.xml in adapters path directory
+            in an asynchronous way, extract the DataReceived/Token and return it
+            as a Deferred which ends up in a JSON-Object (as above).
+
+            see: https://twistedmatrix.com/documents/8.0.0/api/twisted.internet.defer.Deferred.html
+
+            Hint: The simple way is to use defer.succeed(), bonus points for doing
+                  it with a callback chain read->parse->convert.
+        """
+        raise NotImplementedError