EXERCISE 1 Enumerate all uppercase/lowercase permutations for any letter specified in \$rule_char_set. Input: word = "medium-one" rule_char_set = "dn" Output: solutions = ["medium-one", "meDium-one", "medium-oNe", "meDium-oNe"] If the character in \$rule_char_set appears more than once in \$word, treat them as independent variables. For example: Input: word = "medium-one" rule_char_set = "m" Output: solutions = ["medium-one", "Medium-one", 'mediuM-one", "MediuM-one"]