I have another question. How do I call my functions? They are showing blank. Here is the code:

```
def area_of_triangle():
b = input("Base: ")
h = input("Height: ")
area = 0.5 * float(b) * float(h)
return "The area of the triangle is " + str(area) + "."
def area_of_square():
l = input("Length: ")
w = input("Width: ")
area = l * w
return "The area of the square is " + str(area) + "."
formula = input("Please type the equation you would like to do. If you dont know type help. ")
if input == "triangle":
area_of_triangle()
if formula == "square":
area_of_square()
if formula == "help":
print("To find the area of a triangle, type the word triangle. To find the area of a square, type the word square.")
```