updated contents from Atlas repo

interfaces/tombola.py

@@ -0,0 +1,25 @@
+from abc import ABCMeta, abstractmethod
+
+
+class Tombola(metaclass=ABCMeta):  # <1>
+
+    @abstractmethod
+    def __init__(self, iterable):  # <2>
+        raise NotImplementedError
+
+    @abstractmethod
+    def load(self):
+        raise NotImplementedError
+
+    @abstractmethod
+    def pop(self):
+        raise NotImplementedError
+
+    def loaded(self):  # <3>
+        try:
+            item = self.pop()
+        except LookupError:
+            return False
+        else:
+            self.load([item])  # put it back
+            return True