文件操作，列表实例NiceHexSpiral

fr = open('letter.txt',mode='r',encoding='utf-8')
plaincode = fr.read()
print('明文:' + plaincode)


print('密文:',end='')
for c in plaincode:
    print(chr(ord(c)+3),end='')

 

fr = open('letter.txt',mode='r',encoding='utf-8')
plaincode = fr.read()
fr.close


fw = open('c_letter.txt',mode='a',encoding='utf-8')
for c in plaincode:
    fw.write(chr(ord(c)+3)
fw.close

fr = open('letter.txt',mode='r',encoding='utf-8')
plaincode = fr.read()
fr.close


fw = open('c_letter.txt',mode='a',encoding='utf-8')
for c in plaincode:
    fw.write(chr(ord(c)-3))
fw.close

import turtle
turtle.speed(10)
colors = ['#B0E2FF','blue','yellow','pink','green','orange']

for i in range(200):
    turtle.pencolor(colors[i%6])
    turtle.forward(i)
    turtle.left(59)
turtle.done()