Mean-Variance-Standard Deviation Calculator ERROR UNBOUND LOCAL ERROR

hello, I got an error messages, as in the title. here’s the link to my code
i need help, please. thank you. mycode

This error means that up to that place in code that was run the calculations variable wasn’t defined. Take a closer look why that may be happening. Keep in mind that python uses indentation for defining blocks of code that belongs together. For example in code like:

if a == 0:
    b = 1

    c = 2

Line with c assignment also will only be run if check a == 0 is True.