Pygame Physics Explanation Script

#!/usr/bin/python3.4
# setup #
import pygame, sys
# setup pygame/window #
mainClock = pygame.time.Clock()
from pygame.locals import *
pygame.init()
pygame.display.set_caption('Physics Explanation')
screen = pygame.display.set_mode((500,500),0,32)

player = pygame.Rect(100,100,40,80)

tiles = [pygame.Rect(200,350,50,50),pygame.Rect(260,320,50,50)]

def collision_test(rect,tiles):
    collisions = []
    for tile in tiles:
        if rect.colliderect(tile):
            collisions.append(tile)
    return collisions

def move(rect,movement,tiles): # movement = [5,2]
    rect.x += movement[0]
    collisions = collision_test(rect,tiles)
    for tile in collisions:
        if movement[0] > 0:
            rect.right = tile.left
        if movement[0] < 0:
            rect.left = tile.right
    rect.y += movement[1]
    collisions = collision_test(rect,tiles)
    for tile in collisions:
        if movement[1] > 0:
            rect.bottom = tile.top
        if movement[1] < 0:
            rect.top = tile.bottom
    return rect

right = False
left = False
up = False
down = False


# loop #
while True:

    # clear display #
    screen.fill((0,0,0))

    movement = [0,0]
    if right == True:
        movement[0] += 5
    if left == True:
        movement[0] -= 5
    if up == True:
        movement[1] -= 5
    if down == True:
        movement[1] += 5

    player = move(player,movement,tiles)

    pygame.draw.rect(screen,(255,255,255),player)

    for tile in tiles:
        pygame.draw.rect(screen,(255,0,0),tile)

    # event handling #
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()
        if event.type == KEYDOWN:
            if event.key == K_RIGHT:
                right = True
            if event.key == K_LEFT:
                left = True
            if event.key == K_DOWN:
                down = True
            if event.key == K_UP:
                up = True
        if event.type == KEYUP:
            if event.key == K_RIGHT:
                right = False
            if event.key == K_LEFT:
                left = False
            if event.key == K_DOWN:
                down = False
            if event.key == K_UP:
                up = False

    # update display #
    pygame.display.update()
    mainClock.tick(60)