The turtle module is unusual. To make it easier for beginning programmers, all methods of the Turtle class are also available as top level functions that operate on the default (unnamed) turtle instance. All methods of the Screen class are also available as top level functions that operate on the default (sole) screen instance. So both this:
import turtle
star = turtle.Turtle() # turtle instance creation
for i in range(5):
star.forward(50) # turtle instance method
star.right(144) # turtle instance method
screen = turtle.Screen() # access sole screen instance
screen.mainloop() # screen instance method
and this:
import turtle
for i in range(5):
turtle.forward(50) # function, default turtle
turtle.right(144)
turtle.done() # function, mainloop() synonym, acts on singular screen instance
are both valid implementations. Many turtle programs end up mixing the functional interface with the object interface. To avoid this, I strongly recommend the following import syntax:
from turtle import Turtle, Screen
This forces the object approach to using turtle, making the functional approach unavailable:
from turtle import Turtle, Screen
star = Turtle() # turtle instance creation
for i in range(5):
star.forward(50) # turtle instance method
star.right(144) # turtle instance method
screen = Screen() # access sole screen instance
screen.mainloop() # screen instance method
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