import turtle
turtle.pensize(10)
turtle.pencolor("black")
turtle.fd(200)
turtle.seth(90)
turtle.fd(200)
turtle.seth(180)
turtle.fd(200)
turtle.seth(-90)
turtle.fd(200)
turtle.done
import turtle as t
t.pensize(2)
for i in range(4):
    t.fd(150)
    t.left(90)
#学会用range
