added chapter map to README

06-1class-func/bingocall.py

@@ -0,0 +1,35 @@
+"""
+# BEGIN BINGO_DEMO
+
+>>> bingo = BingoCage(range(3))
+>>> bingo.pick()
+1
+>>> bingo()
+0
+>>> callable(bingo)
+True
+
+# END BINGO_DEMO
+
+"""
+
+# BEGIN BINGO
+
+import random
+
+class BingoCage:
+
+    def __init__(self, items):
+        self._items = list(items)  # <1>
+        random.shuffle(self._items)  # <2>
+
+    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