merge in next_gen branch

toxygen/common/provider.py

@@ -0,0 +1,13 @@
+
+
+class Provider:
+
+    def __init__(self, get_item_action):
+        self._get_item_action = get_item_action
+        self._item = None
+
+    def get_item(self):
+        if self._item is None:
+            self._item = self._get_item_action()
+
+        return self._item