diff --git a/code/09/class.ipynb b/code/09/class.ipynb
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+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "source": [
+    "# 理性认识「类与对象」"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%% md\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 29,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "True\n"
+     ]
+    }
+   ],
+   "source": [
+    "class Human:\n",
+    "    eyes = 2\n",
+    "    hands = 2\n",
+    "    legs = 2\n",
+    "    has_hair = True\n",
+    "\n",
+    "    def walk(self):\n",
+    "        print(\"Walking\")\n",
+    "\n",
+    "    def run(self):\n",
+    "        print(\"Running\")\n",
+    "\n",
+    "    def think(self):\n",
+    "        print(\"Thinking\")\n",
+    "\n",
+    "\n",
+    "def is_human(obj):\n",
+    "    if (\n",
+    "        (hasattr(obj, \"eyes\") and getattr(obj, \"eyes\") == 2)\n",
+    "        and (hasattr(obj, \"hands\") and getattr(obj, \"hands\") == 2)\n",
+    "        and (hasattr(obj, \"legs\") and getattr(obj, \"legs\") == 2)\n",
+    "        and (hasattr(obj, \"has_hair\") and getattr(obj, \"has_hair\") == True)\n",
+    "        and hasattr(obj, \"walk\")\n",
+    "        and hasattr(obj, \"run\")\n",
+    "        and hasattr(obj, \"think\")\n",
+    "    ):\n",
+    "        return True\n",
+    "    return False\n",
+    "\n",
+    "\n",
+    "obj = Human()\n",
+    "print(is_human(obj))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 30,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "obj.eyes: 2\n"
+     ]
+    }
+   ],
+   "source": [
+    "print(f\"obj.eyes: {obj.eyes}\")"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 31,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "obj.hands: 2\n"
+     ]
+    }
+   ],
+   "source": [
+    "print(f\"obj.hands: {obj.hands}\")"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 32,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "obj.legs: 2\n"
+     ]
+    }
+   ],
+   "source": [
+    "print(f\"obj.legs: {obj.legs}\")"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 33,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "obj.has_hair: True\n"
+     ]
+    }
+   ],
+   "source": [
+    "print(f\"obj.has_hair: {obj.has_hair}\")"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 34,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Walking\n"
+     ]
+    }
+   ],
+   "source": [
+    "obj.walk()"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 35,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Running\n"
+     ]
+    }
+   ],
+   "source": [
+    "obj.run()"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 36,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Thinking\n"
+     ]
+    }
+   ],
+   "source": [
+    "obj.think()"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "## 属性和方法"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%% md\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 37,
+   "outputs": [],
+   "source": [
+    "class MatrixFactory:  # 1\n",
+    "    name = \"Matrix\"  # 2\n",
+    "\n",
+    "    def echo(self):  # 3\n",
+    "        print(\"Welcome to the Matrix\")\n",
+    "\n",
+    "\n",
+    "matrix = MatrixFactory()  # 4"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 38,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Matrix\n"
+     ]
+    }
+   ],
+   "source": [
+    "print(matrix.name)  # 5"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 39,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Welcome to the Matrix\n"
+     ]
+    }
+   ],
+   "source": [
+    "matrix.echo()  # 6"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "## 构造"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%% md\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 40,
+   "outputs": [],
+   "source": [
+    "class Nation:  # 1\n",
+    "    def __init__(self, name=None):  # 2\n",
+    "        if not name:\n",
+    "            self.name = \"China\"\n",
+    "        else:\n",
+    "            self.name = name\n"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 41,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "China\n"
+     ]
+    }
+   ],
+   "source": [
+    "china = Nation()  # 3\n",
+    "print(china.name)  # 4"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 42,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "USA\n"
+     ]
+    }
+   ],
+   "source": [
+    "usa = Nation(name=\"USA\")  # 5\n",
+    "print(usa.name)  # 6"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 43,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "robot address: 140602200206592\n",
+      "self address: 140602200206592\n"
+     ]
+    }
+   ],
+   "source": [
+    "\n",
+    "class Robot:  # 1\n",
+    "    def show_self(self):  # 2\n",
+    "        print(f\"self address: {id(self)}\")\n",
+    "\n",
+    "\n",
+    "robot = Robot()  # 3\n",
+    "print(f\"robot address: {id(robot)}\")  # 4\n",
+    "robot.show_self()  # 5\n"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 44,
+   "outputs": [],
+   "source": [
+    "# error example\n",
+    "\n",
+    "# class Error:  # 1\n",
+    "#     def raise_error():  # 2\n",
+    "#         print(\"error\")\n",
+    "#\n",
+    "#\n",
+    "# err = Error()  # 3\n",
+    "# err.raise_error()  # 4"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 45,
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "error\n"
+     ]
+    }
+   ],
+   "source": [
+    "class Error:\n",
+    "    def raise_error(err):  # 1\n",
+    "        print(\"error\")\n",
+    "\n",
+    "\n",
+    "err = Error()\n",
+    "err.raise_error()"
+   ],
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   }
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.6"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
\ No newline at end of file