# Check that users have entered a valid
# option based on a list
ans = ""
tf = ""

def string_checker(user_response, valid_ans):

    user_response = user_response.lower()
    while True:
        if user_response in valid_ans:
            return user_response
            break
        else:
            print("please enter yes/no")
            continue

while True:
    ans = input("morb?")
    tf = string_checker(ans, ["yes","no"])
    if tf == "yes":
        print(f"you picked yes")
        break
    else:
        print(f"you picked no")
        break