Update page 'Day 2 homework'

Day 2 homework.md

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+1. Annotate the following python expressions with the specific types of each literal, as well as the overall return value:
+
+* i = 3
+* f = 3.0
+* c = 3+3i
+* b = b'abcdefg'
+* s = 'abcdefg'
+* s = "abcdefg"
+
+2. For each of the types string, bytestring, integer, floating point, and imaginary literals, construct a 5x5 table showing what happens when the character "0" or number 0 is compared to each other type.
+3. Now do the same thing for the + and == operators for each pair of types two other 5x5 tables.
+4. Write a small program that uses the AST module to open the lexer/parser example, and dumps the resulting AST.  See if there are any arguments to parse method which make the output easier to read.
+5. What does this do?  `print("\007")`  Can you figure out why?
+6. What does this do?  `print("abcdefg\rhijklmnop")`  Can you figure out why?
+7. This is a HTTP server.  Run it and connect to http://localhost:8000 .  Why doesn't this do the same thing as what you see above?  
+
+```
+import http.server
+import socketserver
+from urllib.parse import urlparse, parse_qs
+
+class MyRequestHandler(http.server.SimpleHTTPRequestHandler):
+    def do_GET(self):
+        self.send_response(200)
+        self.send_header('Content-type', 'text/plain')
+        self.end_headers()
+        output_string = "abcdefg\rhijklmnop"
+        self.wfile.write(output_string.encode())
+
+PORT = 8000
+Handler = MyRequestHandler
+httpd = socketserver.TCPServer(("", PORT), Handler)
+print(f"Serving on port {PORT}")
+
+httpd.serve_forever()
+```
+8. Think of a way someone might try to commit a crime or hide an embezzlement scheme using the answers to the above two questions.  Hint: applications usually output on web pages, but developers and system administrators usually troubleshoot in the console.
+9. Think of how you would do input validation to prevent such a crime.  Replace the code REPLACE ME here so the tests pass:
+
+```
+def validate(str):
+    for char in str:
+        if REPLACE ME:
+            raise ValueError("Crime detected!")
+
+try:
+    validate("abcdefg")
+    print("✅ test1 pass!")
+except:
+    print("❌ test1 pass!")
+
+try:
+    validate("abcdefg\rhijklmnop")
+    print("❌ test2 fail!")
+except ValueError as err:
+    print("✅ test2 pass!")
+```
+
+