Question $5-$ Regular Expressions $(16$ Pts$)$

You are expected to implement the following tasks by using Regular Expressions. Write functions that take string arguments and print the results in each task below.

$[$Task$-5\mathrm{.}1](4$ Pts$)$ Write a function to find all occurrences of $"$py$"$ followed by zero or more $"$y$"$ characters.

$[$Task$-5\mathrm{.}2](4$ Pts$)$ Write a function to find all digits or sequences of digits in the argument.

$4$

$[$Task$-5\mathrm{.}3](4$ Pts$)$ Write a three$-$argument function to find all words starting with the letter in the first argument and ending with the letter in the second argument. All letters of the words should be lowercase.

$[$Task$-5\mathrm{.}4](4$ Pts$)$ Write a two$-$argument function to replace all whitespace characters with the character in the first argument.