I need to write a python code. These are the instructions.

"Implement the following problem as a self-contained python module. Write a program that continually prompts the user for positive integer values and stores them in a list. You should stop prompting when the user enters a negative integer value. When the user is done entering values, you should print the list of integers they have provided in sorted order. You should then compute the mean and standard deviation of the values in the list. You should not be using any built in modules that calculate variance/standard deviation for you,"

I know I need to use a list function for this but I'm wondering about using a for vs. while loop.