need an explanation for these codes

[15] Define a recursive function total for computing the sum of all the elements of a nested list of integers. You are not allowed to use the built-in function sum, for loop, or while loop. Examples: >>> total(1) >>> total([1,2,3,[4]]]) 10 >>> total([[[5]], [[2],[3],[4]]]) >>> X = total([[[9]]]) 14 >>> X 9 Answer: def total(1st): 8. [15] Consider the following figure of a number key-pad. 2 3 4 5 6 8 9 0 a Phone mnemonic is a way for encoding the Latin alphabet using a traditional telephone key-pad, as shown above. Using this mnemonic, we can encode a telephone number into an alphanumeric string. For example: the character 'A' is translated to the digit 2, and so are 'B' and 'C'. Define a function translate(astr) which accepts a string which may contain upper-case letters, digits, and other characters, and then returns a string obtained by translating all letters in astr into digits according to the telephone key-pad above. Digits and other characters do not change. Examples: >>> translate('PILIHAN JAMAK) *7454426 52625 >>> translate('1-800-PIZZA-ENAK) '1-800-74992-3625 >>> translate('')