ALL SOLUTIONS MUST BE IN PYTHON (3.5) AND BE RECURSIVE FUNCTIONS

a) Write a definition of a function called product. The function receives two parameters containing integer values. You may assume that neither parameter is negative. The function returns the product of the parameters. So, product(3,5) returns 15. The function must not use a loop of any kind (for, while, do-while).

b) The sum of the numbers 1 to n can be calculated recursively as follows:

The sum from 1 to 1 is 1.

The sum from 1 to n is n more than the sum from 1 to n-1

Write a function named sum that accepts a variable containing an integer value as its parameter and returns the sum of the numbers from 1 to to the parameter (calculated recursively).

c) Write a recursive function, len, that accepts a parameter that holds a string value, and returns the number of characters in the string. The length of the string is:

0 if the string is empty ("")

1 more than the length of the string beyond the first character