(a) Write a program that uses a while loop (not a for loop) to read through a string and print the characters of the string one-by-one on separate lines. (b) Modify the program above to print out every second character of the string.

A good program will make sure that the data its users enter is valid. Write a program that asks the user for a weight and converts it from kilograms to pounds. Whenever the user enters a weight below 0, the program should tell them that their entry is invalid and then ask them again to enter a weight. [Hint: Use a while loop, not an if statement].

using python please