[Tutor] I cant fix this bug

[Gina]

I have Python version 3.
when the program begins, it prints out the main menu and then asks you 
for your choice - just like it is supposed to
you enter your choice, and the next menu pops up, and below the menu it 
says "None" on the line before your next choice is asked for
i dont know why it does this or how to make it go away

sorry the menu looks funny(they are supposed to be shapes)
i didnt include the code for all of the functions but the same thing 
happens for each of the four choices

CODE BEGINS HERE:

def parallelogram_area(side1, side2):
     "find the area of a parallelogram"""
     solution1 = float(side1 * side2)
     return solution1

def quadrilateral_perimeter(side1, side2, side3, side4):
     """find the perimeter of a quadralateral"""
     solution1 = float(side1 + side2 + side3  + side4)
     return solution1

def trapezoid_area(side1, side2, height):
     """find the area of a trapazoid"""
     solution1 = float(side1 + side2)
     solution2 = float((height)/2)
     solution3 = float(solution1 * solution2)
     return solution3

def menu_quad():
     """Display menu for quadrilaterals"""
     print(
     """
         Quadrilaterals

     0 - Return to main menu
     1 - Parallelogram (area)
     2 - Trapezoid (area)
     3 - Quadrilateral(perimeter)
     """
     )

choice = None
while choice != "0":
     print(
     """
     Menu

     0 - Exit

     1 - Quadrilaterals        3 - Circles
       _________________             **
      |                 |         ********
      |                 |       ************
      |                 |      **************
      |                 |      **************
      |                 |       ************
      |_________________|         ********
                                     **
      2 - Triangles            4 - 3D
            /\                    /|\
           /  \                  / | \
          /    \                /  |  \
         /      \              /   |  /
        /        \            /    | /
       /__________\          /_____|/

     """
     )

     choice = input("Choice: ")

     if choice == "0":
         print("Good-bye.")

#main
     if choice == "1":
         #quadrilaterals
         print(menu_quad())

         quad_choice = input("Choice: ")

         if quad_choice == "0":
             print()

         if quad_choice == "1":
             #parallelogram
             side1 = float(input("Side 1: "))
             side2 = float(input("Side 2: "))
             area = parallelogram_area(side1, side2)
             print("The area of the parallelogram is", area)

         if quad_choice == "2":
             #trapezoid
             side1 = float(input("Side 1: "))
             side2 = float(input("Side 2: "))
             height = float(input("height: "))
             area = trapezoid_area(side1, side2, height)
             print("The area of the trapezoid is", area)

         if quad_choice == "3":
             #quadrilateral
             side1 = float(input("Side 1: "))
             side2 = float(input("Side 2: "))
             side3 = float(input("Side 3: "))
             side4 = float(input("Side 4: "))
             perim = quadrilateral_perimeter(side1, side2, side3, side4)
             print("The perimeter of the quadrilateral is", perim)

         else:
             print("Sorry, that is not a valid choice :(")

input("Press enter to exit.")