update from Atlas with major reorg

05-1class-func/bingocall.py

@@ -2,12 +2,13 @@
 # BEGIN BINGO_DEMO
 
 >>> bingo = BingoCage(range(3))
->>> bingo()
-2
+>>> bingo.pick()
+1
 >>> bingo()
 0
 >>> callable(bingo)
 True
+
 # END BINGO_DEMO
 
 """
@@ -22,9 +23,13 @@ class BingoCage:
         self._items = list(items)  # <1>
         random.shuffle(self._items)  # <2>
 
-    def __call__(self):
-        if not self._items:  # <3>
-            raise IndexError('pop from empty BingoCage')
-        return self._items.pop()
+    def pick(self):  # <3>
+        try:
+            return self._items.pop()
+        except IndexError:
+            raise LookupError('pick from empty BingoCage')  # <4>
+
+    def __call__(self):  # <5>
+        return self.pick()
 
 # END BINGO