pythonthings
diff --git a/‎stream/client.py
+30-2 b/‎stream/client.py
+30-2
@@ -6,6 +6,8 @@
 import jwt
 import requests
 from requests.adapters import HTTPAdapter
+from stream.serializer import _datetime_encoder
+
 from stream import exceptions, serializer
 from stream.httpsig.requests_auth import HTTPSignatureAuth
 from stream.signing import sign
@@ -304,9 +306,7 @@ def update_activities(self, activities):
             raise TypeError('Activities parameter should be of type list')
 
         auth_token = self.create_jwt_token('activities', '*', feed_id='*')
-
         data = dict(activities=activities)
-
         return self.post('activities/', auth_token, data=data)
 
     def update_activity(self, activity):
@@ -315,6 +315,34 @@ def update_activity(self, activity):
         '''
         return self.update_activities([activity])
 
+    def get_activities(self, ids=None, foreign_id_time=None):
+        '''
+        Retrieves activities by their ID or foreign_id + time combination
+
+        ids: list of activity IDs
+        foreign_id_time: list of tuples (foreign_id, time)
+        '''
+        auth_token = self.create_jwt_token('activities', '*', feed_id='*')
+
+        if ids is None and foreign_id_time is None:
+            raise TypeError('One the parameters ids or foreign_id_time must be provided and not None')
+
+        if ids is not None and foreign_id_time is not None:
+            raise TypeError('At most one of the parameters ids or foreign_id_time must be provided')
+
+        query_params = {}
+
+        if ids is not None:
+            query_params['ids'] = ','.join(ids)
+
+        if foreign_id_time is not None:
+            foreign_ids, timestamps = zip(*foreign_id_time)
+            timestamps = map(_datetime_encoder, timestamps)
+            query_params['foreign_ids'] = ','.join(foreign_ids)
+            query_params['timestamps'] = ','.join(timestamps)
+
+        return self.get('activities/', auth_token, params=query_params)
+
     def create_redirect_url(self, target_url, user_id, events):
         '''
         Creates a redirect url for tracking the given events in the context