added chapter map to README

10-obj-ref/twilight_bus.py

@@ -0,0 +1,26 @@
+"""
+>>> basketball_team = ['Sue', 'Tina', 'Maya', 'Diana', 'Pat']
+>>> bus = TwilightBus(basketball_team)
+>>> bus.drop('Tina')
+>>> bus.drop('Pat')
+>>> basketball_team
+['Sue', 'Maya', 'Diana']
+"""
+
+# BEGIN TWILIGHT_BUS_CLASS
+class TwilightBus:
+    """A bus model that makes passengers vanish"""
+
+    def __init__(self, passengers=None):
+        if passengers is None:
+            self.passengers = []  # <1>
+        else:
+            self.passengers = passengers  #<2>
+
+    def pick(self, name):
+        self.passengers.append(name)
+
+    def drop(self, name):
+        self.passengers.remove(name)  # <3>
+# END TWILIGHT_BUS_CLASS
+