A program that takes user input and draws pattern of astrologer's stars

while True:

    try:

        print("How many rows of stars you want?")

        nr = int(input())

    except:

        print("Wrong input! Only numbers allowed.")

        continue

    print("""Keys:

    Just press Enter for inverted pattern or

    Type anything and press Enter for upright pattern.""")

    tf = bool(input())

    i=0

    if tf == True:

        while i<nr:

            print("*"*(i+1))

            i+=1

    else:

        while i<nr:

            print("*"*(nr-i))

            i+=1