Implementing valid_puzzle(puzzle: list) -> bool function (4 marks)
This function takes one argument puzzle which is a list of strings. This function returns
Boolean True if the puzzle is valid and Boolean False otherwise. A valid puzzle contains
strings of equal length. For example, given the following three puzzles, puzzle1 is valid
whilst puzzle2 (not all strings are the same length) and puzzle3 (contain item that is not a
string) are invalid. The strings in the puzzle are case insensitive. You may decide to convert
the strings to uppercase.