lec12 & 13 updated

df587723 · gsingh58 · 26470de5 · df587723 · df587723 · df587723
Commit df587723 authored 1 year ago by gsingh58
--- a/lecture_material/12-web-2/solution.ipynb
+++ b/lecture_material/12-web-2/solution.ipynb
@@ -27,11 +27,30 @@
   "source": [
    "### Rate-limited webpage parsing\n",
    "\n",
+    "\n",
    "- `requests` module:\n",
    "    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request\n",
    "    - `resp.status_code`: status code of the response\n",
    "    - `resp.text`: `str` text content of the response\n",
-    "    - `resp.headers`: `dict` content of response headers"
+    "    - `resp.headers`: `dict` content of response headers\n",
+    "    \n",
+    "- `@` operator is called a \"decorator\"\n",
+    "- `flask.Response`: enables us to create a response object instance\n",
+    "    - Arguments: `str` representing reponse, `headers` dict representing metadata, `status` representing status code.\n",
+    "    - ex: \n",
+    "    ```python\n",
+    "    flask.Response(\"<b>go away</b>\",\n",
+    "                              status=429,\n",
+    "                              headers={\"Retry-After\": \"3\"})\n",
+    "    ```\n",
+    "    \n",
+    "    ```python\n",
+    "    flask.Response(\"\"\"User-Agent: *\n",
+    "    Disallow: /never\n",
+    "    \"\"\", headers={\"Content-Type\": \"text/plain\"})\n",
+    "    ```\n",
+    "\n",
+    "- `flask.request.remote_addr`: enables us to take action based on the IP address from which we receive the request"
   ]
  },
  {
@@ -73,7 +92,7 @@
    "        resp.raise_for_status() # raise exception if not 200\n",
    "        return resp\n",
    "    \n",
-    "friendly_get(base_url + \"/slow\").text"
+    "friendly_get(base_url + \"slow\").text"
   ]
  }
 ],

 %% Cell type:markdown id:cf313adf tags:

 # Web 2: Flask

 %% Cell type:code id:d55e4bb4-9f29-4f4f-bba6-05054718259b tags:

 ``` python
 import requests
 import time
 import urllib.robotparser
 ```

 %% Cell type:markdown id:527600aa tags:

 ### Rate-limited webpage parsing

+
 - `requests` module:
    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request
    - `resp.status_code`: status code of the response
    - `resp.text`: `str` text content of the response
    - `resp.headers`: `dict` content of response headers

+- `@` operator is called a "decorator"
+- `flask.Response`: enables us to create a response object instance
+    - Arguments: `str` representing reponse, `headers` dict representing metadata, `status` representing status code.
+    - ex:
+    ```python
+    flask.Response("<b>go away</b>",
+                              status=429,
+                              headers={"Retry-After": "3"})
+    ```
+
+    ```python
+    flask.Response("""User-Agent: *
+    Disallow: /never
+    """, headers={"Content-Type": "text/plain"})
+    ```
+
+- `flask.request.remote_addr`: enables us to take action based on the IP address from which we receive the request
+
 %% Cell type:code id:8241e51c tags:

 ``` python
 base_url = "http://34.123.132.20:5000/"
 ```

 %% Cell type:code id:6cc81b85 tags:

 ``` python
 def friendly_get(url):
    while True:
        resp = requests.get(url)
        if resp.status_code == 429:
            seconds = int(resp.headers.get("Retry-After", 1))
            print(f"sleep {seconds}")
            time.sleep(seconds)
            continue
        resp.raise_for_status() # raise exception if not 200
        return resp

-friendly_get(base_url + "/slow").text
+friendly_get(base_url + "slow").text
 ```

 %% Output

    'welcome!'

--- a/lecture_material/12-web-2/solution.py
+++ b/lecture_material/12-web-2/solution.py
 import flask # requires installation if not already installed - pip3 install flask
 import time
-import json
+# import json

 app = flask.Flask("my application") # name of the web application can be anything


--- a/lecture_material/12-web-2/template_lec_001.ipynb
+++ b/lecture_material/12-web-2/template_lec_001.ipynb
@@ -26,11 +26,30 @@
   "source": [
    "### Rate-limited webpage parsing\n",
    "\n",
+    "\n",
    "- `requests` module:\n",
    "    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request\n",
    "    - `resp.status_code`: status code of the response\n",
    "    - `resp.text`: `str` text content of the response\n",
-    "    - `resp.headers`: `dict` content of response headers"
+    "    - `resp.headers`: `dict` content of response headers\n",
+    "    \n",
+    "- `@` operator is called a \"decorator\"\n",
+    "- `flask.Response`: enables us to create a response object instance\n",
+    "    - Arguments: `str` representing reponse, `headers` dict representing metadata, `status` representing status code.\n",
+    "    - ex: \n",
+    "    ```python\n",
+    "    flask.Response(\"<b>go away</b>\",\n",
+    "                              status=429,\n",
+    "                              headers={\"Retry-After\": \"3\"})\n",
+    "    ```\n",
+    "    \n",
+    "    ```python\n",
+    "    flask.Response(\"\"\"User-Agent: *\n",
+    "    Disallow: /never\n",
+    "    \"\"\", headers={\"Content-Type\": \"text/plain\"})\n",
+    "    ```\n",
+    "\n",
+    "- `flask.request.remote_addr`: enables us to take action based on the IP address from which we receive the request"
   ]
  },
  {

 %% Cell type:markdown id:cf313adf tags:

 # Web 2: Flask

 %% Cell type:code id:d55e4bb4-9f29-4f4f-bba6-05054718259b tags:

 ``` python
 import requests
 import time
 ```

 %% Cell type:markdown id:527600aa tags:

 ### Rate-limited webpage parsing

+
 - `requests` module:
    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request
    - `resp.status_code`: status code of the response
    - `resp.text`: `str` text content of the response
    - `resp.headers`: `dict` content of response headers

+- `@` operator is called a "decorator"
+- `flask.Response`: enables us to create a response object instance
+    - Arguments: `str` representing reponse, `headers` dict representing metadata, `status` representing status code.
+    - ex:
+    ```python
+    flask.Response("<b>go away</b>",
+                              status=429,
+                              headers={"Retry-After": "3"})
+    ```
+
+    ```python
+    flask.Response("""User-Agent: *
+    Disallow: /never
+    """, headers={"Content-Type": "text/plain"})
+    ```
+
+- `flask.request.remote_addr`: enables us to take action based on the IP address from which we receive the request
+
 %% Cell type:code id:8241e51c tags:

 ``` python
 base_url = "http://34.123.132.20:5000/"
 ```

 %% Cell type:code id:6cc81b85 tags:

 ``` python
 def friendly_get(url):
    while True:
        resp = requests.get(url)
        resp.raise_for_status() # raise exception if not 200
        return resp

 friendly_get(base_url + "/slow").text
 ```

--- a/lecture_material/12-web-2/template_lec_001.py
+++ b/lecture_material/12-web-2/template_lec_001.py
 import flask # requires installation if not already installed - pip3 install flask
 import time
-import json
+

 app = flask.Flask("my application") # name of the web application can be anything

@@ -18,8 +18,7 @@ last_visit = 0 # TODO: dict of visit times, for each IP
 # TODO: create a dynamic page ha.html
 # DYNAMIC

-# STATIC
-# @ operator is called a "decorator"
+
 # STATIC
 # @ operator is called a "decorator"
 @app.route("/")

--- a/lecture_material/12-web-2/template_lec_002.ipynb
+++ b/lecture_material/12-web-2/template_lec_002.ipynb
@@ -26,11 +26,30 @@
   "source": [
    "### Rate-limited webpage parsing\n",
    "\n",
+    "\n",
    "- `requests` module:\n",
    "    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request\n",
    "    - `resp.status_code`: status code of the response\n",
    "    - `resp.text`: `str` text content of the response\n",
-    "    - `resp.headers`: `dict` content of response headers"
+    "    - `resp.headers`: `dict` content of response headers\n",
+    "    \n",
+    "- `@` operator is called a \"decorator\"\n",
+    "- `flask.Response`: enables us to create a response object instance\n",
+    "    - Arguments: `str` representing reponse, `headers` dict representing metadata, `status` representing status code.\n",
+    "    - ex: \n",
+    "    ```python\n",
+    "    flask.Response(\"<b>go away</b>\",\n",
+    "                              status=429,\n",
+    "                              headers={\"Retry-After\": \"3\"})\n",
+    "    ```\n",
+    "    \n",
+    "    ```python\n",
+    "    flask.Response(\"\"\"User-Agent: *\n",
+    "    Disallow: /never\n",
+    "    \"\"\", headers={\"Content-Type\": \"text/plain\"})\n",
+    "    ```\n",
+    "\n",
+    "- `flask.request.remote_addr`: enables us to take action based on the IP address from which we receive the request"
   ]
  },
  {
@@ -56,7 +75,7 @@
    "        resp.raise_for_status() # raise exception if not 200\n",
    "        return resp\n",
    "    \n",
-    "friendly_get(base_url + \"/slow\").text"
+    "friendly_get(base_url + \"slow\").text"
   ]
  }
 ],

 %% Cell type:markdown id:cf313adf tags:

 # Web 2: Flask

 %% Cell type:code id:d55e4bb4-9f29-4f4f-bba6-05054718259b tags:

 ``` python
 import requests
 import time
 ```

 %% Cell type:markdown id:527600aa tags:

 ### Rate-limited webpage parsing

+
 - `requests` module:
    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request
    - `resp.status_code`: status code of the response
    - `resp.text`: `str` text content of the response
    - `resp.headers`: `dict` content of response headers

+- `@` operator is called a "decorator"
+- `flask.Response`: enables us to create a response object instance
+    - Arguments: `str` representing reponse, `headers` dict representing metadata, `status` representing status code.
+    - ex:
+    ```python
+    flask.Response("<b>go away</b>",
+                              status=429,
+                              headers={"Retry-After": "3"})
+    ```
+
+    ```python
+    flask.Response("""User-Agent: *
+    Disallow: /never
+    """, headers={"Content-Type": "text/plain"})
+    ```
+
+- `flask.request.remote_addr`: enables us to take action based on the IP address from which we receive the request
+
 %% Cell type:code id:8241e51c tags:

 ``` python
 base_url = "http://34.123.132.20:5000/"
 ```

 %% Cell type:code id:6cc81b85 tags:

 ``` python
 def friendly_get(url):
    while True:
        resp = requests.get(url)
        resp.raise_for_status() # raise exception if not 200
        return resp

-friendly_get(base_url + "/slow").text
+friendly_get(base_url + "slow").text
 ```

--- a/lecture_material/12-web-2/template_lec_002.py
+++ b/lecture_material/12-web-2/template_lec_002.py
 import flask # requires installation if not already installed - pip3 install flask
 import time
-import json

 app = flask.Flask("my application") # name of the web application can be anything

@@ -18,8 +17,7 @@ last_visit = 0 # TODO: dict of visit times, for each IP
 # TODO: create a dynamic page ha.html
 # DYNAMIC

-# STATIC
-# @ operator is called a "decorator"
+
 # STATIC
 # @ operator is called a "decorator"
 @app.route("/")

--- a/lecture_material/13-web-3/solution.ipynb
+++ b/lecture_material/13-web-3/solution.ipynb
@@ -22,16 +22,18 @@
  },
  {
   "cell_type": "markdown",
-   "id": "527600aa",
+   "id": "725234ef-a02b-47da-bfec-aaa16e852a58",
   "metadata": {},
   "source": [
-    "### Rate-limited webpage parsing\n",
-    "\n",
-    "- `requests` module:\n",
-    "    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request\n",
-    "    - `resp.status_code`: status code of the response\n",
-    "    - `resp.text`: `str` text content of the response\n",
-    "    - `resp.headers`: `dict` content of response headers"
+    "- `flask.request.args`: enables us to get the arguments passed as part of the URL\n",
+    "    - How do we pass arguments?\n",
+    "        - at the end of the URL, add a \"?\"\n",
+    "        - then separate argument-value pair by \"=\"\n",
+    "        - use \"&\" as delimiter between two argument-value pairs\n",
+    "    - examples: \n",
+    "        - http://34.123.132.20:5000/add?x=10&y=20\n",
+    "        - http://34.123.132.20:5000/survey?major=CS\n",
+    "        - http://34.123.132.20:5000/survey?major=Mechanical_Engineering"
   ]
  },
  {
@@ -87,7 +89,7 @@
    {
     "data": {
      "text/plain": [
-       "True"
+       "False"
      ]
     },
     "execution_count": 4,
@@ -96,7 +98,7 @@
    }
   ],
   "source": [
-    "rp.can_fetch(\"cs320bot\", base_url + \"/never\")"
+    "rp.can_fetch(\"cs320bot\", base_url + \"never\")"
   ]
  },
  {
@@ -130,7 +132,7 @@
    "        resp.raise_for_status() # raise exception if not 200\n",
    "        return resp\n",
    "    \n",
-    "friendly_get(base_url + \"/slow\").text"
+    "friendly_get(base_url + \"slow\").text"
   ]
  }
 ],

 %% Cell type:markdown id:cf313adf tags:

 # Web 3: More Flask

 %% Cell type:code id:d55e4bb4-9f29-4f4f-bba6-05054718259b tags:

 ``` python
 import requests
 import time
 import urllib.robotparser
 ```

-%% Cell type:markdown id:527600aa tags:
+%% Cell type:markdown id:725234ef-a02b-47da-bfec-aaa16e852a58 tags:

-### Rate-limited webpage parsing
-
- `requests` module:
-    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request
-    - `resp.status_code`: status code of the response
-    - `resp.text`: `str` text content of the response
-    - `resp.headers`: `dict` content of response headers
+- `flask.request.args`: enables us to get the arguments passed as part of the URL
+    - How do we pass arguments?
+        - at the end of the URL, add a "?"
+        - then separate argument-value pair by "="
+        - use "&" as delimiter between two argument-value pairs
+    - examples:
+        - http://34.123.132.20:5000/add?x=10&y=20
+        - http://34.123.132.20:5000/survey?major=CS
+        - http://34.123.132.20:5000/survey?major=Mechanical_Engineering

 %% Cell type:code id:8241e51c tags:

 ``` python
 base_url = "http://34.123.132.20:5000/"
 ```

 %% Cell type:markdown id:23ba100b tags:

 ### `urllib.robotparser`

 - Documentation: https://docs.python.org/3/library/urllib.robotparser.html

 %% Cell type:code id:379c3ae5-7344-45b1-88c3-b35f0bd8eb5b tags:

 ``` python
 rp = urllib.robotparser.RobotFileParser()
 rp.set_url(base_url + "/robots.txt")
 rp.read()
 rp.can_fetch("cs320bot", base_url + "/slow")
 ```

 %% Output

    True

 %% Cell type:code id:2e3fb01c-4281-4cbf-8828-98e04d27d09a tags:

 ``` python
-rp.can_fetch("cs320bot", base_url + "/never")
+rp.can_fetch("cs320bot", base_url + "never")
 ```

 %% Output

-    True
+    False

 %% Cell type:code id:6cc81b85 tags:

 ``` python
 def friendly_get(url):
    if not rp.can_fetch("cs320bot", url):
        raise Exception("you're not supposed to visit that page")
    while True:
        resp = requests.get(url)
        if resp.status_code == 429:
            seconds = int(resp.headers.get("Retry-After", 1))
            print(f"sleep {seconds}")
            time.sleep(seconds)
            continue
        resp.raise_for_status() # raise exception if not 200
        return resp

-friendly_get(base_url + "/slow").text
+friendly_get(base_url + "slow").text
 ```

 %% Output

    'welcome!'

--- a/lecture_material/13-web-3/solution.py
+++ b/lecture_material/13-web-3/solution.py
 import flask # requires installation if not already installed - pip3 install flask
 import time
-import json
+# import json

 app = flask.Flask("my application") # name of the web application can be anything


--- a/lecture_material/13-web-3/template_lec_001.ipynb
+++ b/lecture_material/13-web-3/template_lec_001.ipynb
@@ -21,16 +21,18 @@
  },
  {
   "cell_type": "markdown",
-   "id": "527600aa",
+   "id": "a5f26f67-000a-4d68-8033-3e46023b8196",
   "metadata": {},
   "source": [
-    "### Rate-limited webpage parsing\n",
-    "\n",
-    "- `requests` module:\n",
-    "    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request\n",
-    "    - `resp.status_code`: status code of the response\n",
-    "    - `resp.text`: `str` text content of the response\n",
-    "    - `resp.headers`: `dict` content of response headers"
+    "- `flask.request.args`: enables us to get the arguments passed as part of the URL\n",
+    "    - How do we pass arguments?\n",
+    "        - at the end of the URL, add a \"?\"\n",
+    "        - then separate argument-value pair by \"=\"\n",
+    "        - use \"&\" as delimiter between two argument-value pairs\n",
+    "    - examples: \n",
+    "        - http://34.123.132.20:5000/add?x=10&y=20\n",
+    "        - http://34.123.132.20:5000/survey?major=CS\n",
+    "        - http://34.123.132.20:5000/survey?major=Mechanical_Engineering"
   ]
  },
  {
@@ -79,10 +81,15 @@
    "def friendly_get(url):\n",
    "    while True:\n",
    "        resp = requests.get(url)\n",
+    "        if resp.status_code == 429:\n",
+    "            seconds = int(resp.headers.get(\"Retry-After\", 1))\n",
+    "            print(f\"sleep {seconds}\")\n",
+    "            time.sleep(seconds)\n",
+    "            continue\n",
    "        resp.raise_for_status() # raise exception if not 200\n",
    "        return resp\n",
    "    \n",
-    "friendly_get(base_url + \"/slow\").text"
+    "friendly_get(base_url + \"slow\").text"
   ]
  }
 ],

 %% Cell type:markdown id:cf313adf tags:

 # Web 3: More Flask

 %% Cell type:code id:d55e4bb4-9f29-4f4f-bba6-05054718259b tags:

 ``` python
 import requests
 import time
 ```

-%% Cell type:markdown id:527600aa tags:
+%% Cell type:markdown id:a5f26f67-000a-4d68-8033-3e46023b8196 tags:

-### Rate-limited webpage parsing
-
- `requests` module:
-    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request
-    - `resp.status_code`: status code of the response
-    - `resp.text`: `str` text content of the response
-    - `resp.headers`: `dict` content of response headers
+- `flask.request.args`: enables us to get the arguments passed as part of the URL
+    - How do we pass arguments?
+        - at the end of the URL, add a "?"
+        - then separate argument-value pair by "="
+        - use "&" as delimiter between two argument-value pairs
+    - examples:
+        - http://34.123.132.20:5000/add?x=10&y=20
+        - http://34.123.132.20:5000/survey?major=CS
+        - http://34.123.132.20:5000/survey?major=Mechanical_Engineering

 %% Cell type:code id:8241e51c tags:

 ``` python
 base_url = "http://34.123.132.20:5000/"
 ```

 %% Cell type:markdown id:23ba100b tags:

 ### `urllib.robotparser`

 - Documentation: https://docs.python.org/3/library/urllib.robotparser.html

 %% Cell type:code id:379c3ae5-7344-45b1-88c3-b35f0bd8eb5b tags:

 ``` python
 ```

 %% Cell type:code id:2e3fb01c-4281-4cbf-8828-98e04d27d09a tags:

 ``` python
 ```

 %% Cell type:code id:6cc81b85 tags:

 ``` python
 def friendly_get(url):
    while True:
        resp = requests.get(url)
+        if resp.status_code == 429:
+            seconds = int(resp.headers.get("Retry-After", 1))
+            print(f"sleep {seconds}")
+            time.sleep(seconds)
+            continue
        resp.raise_for_status() # raise exception if not 200
        return resp

-friendly_get(base_url + "/slow").text
+friendly_get(base_url + "slow").text
 ```

--- a/lecture_material/13-web-3/template_lec_001.py
+++ b/lecture_material/13-web-3/template_lec_001.py
 import flask # requires installation if not already installed - pip3 install flask
 import time
-import json

 app = flask.Flask("my application") # name of the web application can be anything

@@ -29,8 +28,6 @@ last_visit = 0 # TODO: dict of visit times, for each IP
 # TODO: create a dynamic page ha.html
 # DYNAMIC

-# STATIC
-# @ operator is called a "decorator"
 # STATIC
 # @ operator is called a "decorator"
 @app.route("/")

--- a/lecture_material/13-web-3/template_lec_002.ipynb
+++ b/lecture_material/13-web-3/template_lec_002.ipynb
@@ -19,6 +19,22 @@
    "import time\n"
   ]
  },
+  {
+   "cell_type": "markdown",
+   "id": "14525019-f30b-40a7-be53-db49868abce6",
+   "metadata": {},
+   "source": [
+    "- `flask.request.args`: enables us to get the arguments passed as part of the URL\n",
+    "    - How do we pass arguments?\n",
+    "        - at the end of the URL, add a \"?\"\n",
+    "        - then separate argument-value pair by \"=\"\n",
+    "        - use \"&\" as delimiter between two argument-value pairs\n",
+    "    - examples: \n",
+    "        - http://34.123.132.20:5000/add?x=10&y=20\n",
+    "        - http://34.123.132.20:5000/survey?major=CS\n",
+    "        - http://34.123.132.20:5000/survey?major=Mechanical_Engineering"
+   ]
+  },
  {
   "cell_type": "markdown",
   "id": "527600aa",
@@ -79,10 +95,15 @@
    "def friendly_get(url):\n",
    "    while True:\n",
    "        resp = requests.get(url)\n",
+    "        if resp.status_code == 429:\n",
+    "            seconds = int(resp.headers.get(\"Retry-After\", 1))\n",
+    "            print(f\"sleep {seconds}\")\n",
+    "            time.sleep(seconds)\n",
+    "            continue\n",
    "        resp.raise_for_status() # raise exception if not 200\n",
    "        return resp\n",
    "    \n",
-    "friendly_get(base_url + \"/slow\").text"
+    "friendly_get(base_url + \"slow\").text"
   ]
  }
 ],

 %% Cell type:markdown id:cf313adf tags:

 # Web 3: More Flask

 %% Cell type:code id:d55e4bb4-9f29-4f4f-bba6-05054718259b tags:

 ``` python
 import requests
 import time
 ```

+%% Cell type:markdown id:14525019-f30b-40a7-be53-db49868abce6 tags:
+
+- `flask.request.args`: enables us to get the arguments passed as part of the URL
+    - How do we pass arguments?
+        - at the end of the URL, add a "?"
+        - then separate argument-value pair by "="
+        - use "&" as delimiter between two argument-value pairs
+    - examples:
+        - http://34.123.132.20:5000/add?x=10&y=20
+        - http://34.123.132.20:5000/survey?major=CS
+        - http://34.123.132.20:5000/survey?major=Mechanical_Engineering
+
 %% Cell type:markdown id:527600aa tags:

 ### Rate-limited webpage parsing

 - `requests` module:
    - `resp = requests.get(<URL>)` method: enables us to send HTTP GET request
    - `resp.status_code`: status code of the response
    - `resp.text`: `str` text content of the response
    - `resp.headers`: `dict` content of response headers

 %% Cell type:code id:8241e51c tags:

 ``` python
 base_url = "http://34.123.132.20:5000/"
 ```

 %% Cell type:markdown id:23ba100b tags:

 ### `urllib.robotparser`

 - Documentation: https://docs.python.org/3/library/urllib.robotparser.html

 %% Cell type:code id:379c3ae5-7344-45b1-88c3-b35f0bd8eb5b tags:

 ``` python
 ```

 %% Cell type:code id:2e3fb01c-4281-4cbf-8828-98e04d27d09a tags:

 ``` python
 ```

 %% Cell type:code id:6cc81b85 tags:

 ``` python
 def friendly_get(url):
    while True:
        resp = requests.get(url)
+        if resp.status_code == 429:
+            seconds = int(resp.headers.get("Retry-After", 1))
+            print(f"sleep {seconds}")
+            time.sleep(seconds)
+            continue
        resp.raise_for_status() # raise exception if not 200
        return resp

-friendly_get(base_url + "/slow").text
+friendly_get(base_url + "slow").text
 ```

--- a/lecture_material/13-web-3/template_lec_002.py
+++ b/lecture_material/13-web-3/template_lec_002.py
 import flask # requires installation if not already installed - pip3 install flask
 import time
-import json

 app = flask.Flask("my application") # name of the web application can be anything

@@ -29,8 +28,6 @@ last_visit = 0 # TODO: dict of visit times, for each IP
 # TODO: create a dynamic page ha.html
 # DYNAMIC

-# STATIC
-# @ operator is called a "decorator"
 # STATIC
 # @ operator is called a "decorator"
 @app.route("/")