$1.$ Write a Python program that prompts the user to enter a number, calculates its square root, and handles the

"ValueError" exception by displaying an appropriate error message when the user enters a negative number.

The program should also write the results to a file named "sart$\_$results.txt$".$

$2.$ Write a python program that reads the contents of a text file and implements error handling using try$-$except$-$finally block to handle exceptions such as "FileNotFoundError" and

"IOError". Print the contents of the file or display appropriate error messages

if any of these exceptions occur during file handling.

$3.$ You're going to write an interactive calculator! User input is assumed to be a formula that consist of a number, an operator $($at least $+$ and $-),$ and another number, separated by white space $($e$.$g$.1+1).$ Split user input using str$.$split, and check whether the resulting list is valid:

If the input does not consist of $3$ elements, raise a FormulaError, which is a custom Exception. Try to convert the first and third input to a float $($like so:

float$\_$value $=$ float$($str$\_$value$)).$ Catch any ValueError that

occurs, and instead raise a FormulaError. If the second input is not $\text{'}+\text{'}$ or$\text{'}-\text{'},$ again raise a FormulaError. If the input is valid, perform the calculation and print out the result. The user is then prompted to provide new input, and so on$,$ until the user enters quit. $($Python Program$)$

$4.$ Write a python program that Define a function capitalize$\_$last$\_$name$()$ that accepts as argument a string with a $($single$)$ first and a $($single$)$ last name, and returns a string in which only the first letter of the first name is uppercase, whereas all letters of the last name are uppercase; in otherwords, 'marisa tomei' becomes 'Marisa TOMEI. $($Tip: use str$.$split$()$ to split a str into separate words.$)$

If something other than a str object is passed as an argument, the function should raise a TypeError. $($Tip: you can use isistance$)$ to check whether an object is of a particular type.$)$ If the str does not consist of exactly two words, the function should raise a ValueError.