# The following program draws a tree
# First, notice that we already know enough Python to do some cool stuff!
# Call the function with different parameters to determine what each of them does
# How does such a simple function result in such a complex figure?
# Notice that only the left side of the tree is drawn; can you also draw the right?
# Play with the idea to see whether you can get other interesting shapes
# Read about fractals on Wikipedia

from turtle import *

def tree(length, angle, step):
    if length < step: # this is a conditional.  It does just what it sounds like -- the statements inside it are only executed if the condition is true
        return # exits the function
    forward(length)
    left(angle)
    tree(length / 2, angle, step)
    right(angle)
    tree(length / 2, angle, step)
    right(angle)
    left(angle)
    backward(length)
speed(100)
left(90)
tree(200, 30, .5)