Hello I need help making these two functions in Python. Thank you.

A recursive function named num_of_ones that takes a single integer parameter and returns the number of ones in the binary representation of the number.

A function named index_list that takes two parameters: a list and an integer with default value of 2. The function will return a list that has only some of the values from the original list, by default every other item (the ones from indices 1, 3, 5, 7, etc.). If the parameter is 3, it will return every fourth item (indices 2, 5, 8, etc.).