a) [10 pts] Define a function called three_sub_str that takes in as input a string and returns a string made of the first 3 and the last 3 characters from the input. If the string length is less than 3, then return the string Not Possible. Examples: 1. Input: 'watermelon'; Output: watlon 2. Input: 'try'; Output: trytry 3. Input: 'as'; Output: Not Possible [6] : #INSERT YOUR ANSWER HERE. b) [10 pts] Define a function five_reverse that takes as input a string and returns the reverse of the string if its length is a multiple of 5; else returns the original string. Examples: 1. Input: 'GreenApple'; Output: 'elppAneerG' 2. Input: 'RedApple'; Output: 'RedApple' [7 ] : #INSERT YOUR ANSWER HERE.c) [10 pts] Define a function count_char that takes in as input a string and a boolean value and returns a dictionary with each character in the string as key and the count of the number of times the character appeared in the string as value. If the boolean value is True , it returns the dictionary with only the most frequent character; else, it returns the entire dictionary. Examples: 1. Input: 'apple', False; Output: {'a': 1, 'p': 2, 'l': '1', 'e': '1'} 2. Input: 'apple', True; Output: {'p': 2} [8] : #INSERT YOUR ANSWER HERE. BONUS [10 pts] Define a function called min_sub_str that takes two string arguments ( S and T ) and returns the first possible substring (traversing from left) containing all the elements of T . For example: given S = 'xBXXxx(XXxxxBXXXAx(xBxxxxxBxCx' and T = "ABC" , return "BxxAxxC" [9] : #INSERT YOUR ANSWER HERE