Fix potential conflicts between triggers and Python keywords

Author: neolee

p2-b-fsm.ipynb

@@ -277,15 +277,15 @@
     "        # 定义状态转换函数\n",
     "        # 基本的语法很好懂，trigger 参数是输入函数名，source 和 dest 分别是当前和转换后的状态\n",
     "        # before 参数表示进行这个状态转换之前要调用的函数，如果该函数运行时出现异常，状态转换会中止\n",
-    "        self.machine.add_transition(trigger='pay', source='created', dest='paid', before='payment_service')\n",
+    "        self.machine.add_transition(trigger='t_pay', source='created', dest='paid', before='payment_service')\n",
     "        # after 参数表示当这个状态转换完成后调用的函数，我们用这个函数来通知用户已经发货在途了\n",
-    "        self.machine.add_transition(trigger='deliver', source='paid', dest='delivering', after='notify_delivering')\n",
-    "        self.machine.add_transition(trigger='receive', source='delivering', dest='received')\n",
-    "        self.machine.add_transition(trigger='confirm', source='received', dest='done')\n",
+    "        self.machine.add_transition(trigger='t_deliver', source='paid', dest='delivering', after='notify_delivering')\n",
+    "        self.machine.add_transition(trigger='t_receive', source='delivering', dest='received')\n",
+    "        self.machine.add_transition(trigger='t_confirm', source='received', dest='done')\n",
     "        # 可以一次定义多个状态向同一个状态的装换\n",
-    "        self.machine.add_transition(trigger='cancel', source=['created', 'paid'], dest='cancelling')\n",
-    "        self.machine.add_transition(trigger='return', source=['delivering', 'received'], dest='returning')\n",
-    "        self.machine.add_transition(trigger='close', source=['cancelling', 'returning'], dest='closed')\n",
+    "        self.machine.add_transition(trigger='t_cancel', source=['created', 'paid'], dest='cancelling')\n",
+    "        self.machine.add_transition(trigger='t_return', source=['delivering', 'received'], dest='returning')\n",
+    "        self.machine.add_transition(trigger='t_close', source=['cancelling', 'returning'], dest='closed')\n",
     "        \n",
     "    def payment_service(self):\n",
     "        print('支付服务申请中……')\n",
@@ -301,11 +301,11 @@
     "order1 = Order(1)\n",
     "order1.state # => 'created'\n",
     "# order1.receive() # => 如果运行这一句会抛出 MachineError 异常，因为当前状态与此 trigger（输入）不匹配，转换不被允许\n",
-    "order1.pay() # => 会先调用 payment_service()，成功的话返回 True\n",
+    "order1.t_pay() # => 会先调用 payment_service()，成功的话返回 True\n",
     "order1.state # => 'paid'\n",
-    "order1.deliver() # => 成功后调用 notify_delivering() 通知用户\n",
-    "order1.receive()\n",
-    "order1.confirm()\n",
+    "order1.t_deliver() # => 成功后调用 notify_delivering() 通知用户\n",
+    "order1.t_receive()\n",
+    "order1.t_confirm()\n",
     "order1.state # => 'done'"
    ]
   },