05-01 import time create snake.walk()

01

import time at top 

import time

use time.sleep(.3) at the bottom of the Game while running loop. Place a self.snake.walk() right before sleep(), Then Create the snake.walk() 

 
self.snake.walk()
time.sleep(.3)

Make sure self.snake.walk() and time.sleep(.3) are indented inside for event in ..

02

Assign a blank value for self.direction inside __init__ for Snake 

 
self.direction = 'down'

Move block movement logic inside walk() 

def walk(self):
    if self.direction ==  'down':
        self.y += 10
    if self.direction == 'up':
        self.y += 10
    if self.direction == 'left':
        self.x -= 10
    if self.direction == 'right':
        self.x += 10
    self.draw()

and inside the move_ methods, change the self.direction 

    def move_down(self):
        self.direction = 'down'
    def move_up(self):
        self.direction = 'up'
    def move_left(self):
        self.direction = 'left'
    def move_right(self):
        self.direction = 'right'

03

This code now allows for constant movement when key is pressed

and inside the move_ methods, change the self.direction 

    def move_down(self):
        self.direction = 'down'
    def move_up(self):
        self.direction = 'up'
    def move_left(self):
        self.direction = 'left'
    def move_right(self):
        self.direction = 'right'