Python 随机大集合，要善于利用 string 里面的常量（ascii_letters, ascii_lowercase, ascii_uppercase, letters, digits, hexdigits, octdigits），减少代码量。

random_example.py

import random, string

# number
number = random.randint(1, 9)

# char
char = chr(random.randint(65, 90))
char = random.choice(string.ascii_letters)

# string
length = random.randint(1, 9)
str = ''.join([random.choice(string.ascii_letters) for i in range(length)])
str = ''.join(random.sample(string.ascii_letters, length))
str = ''.join([(string.ascii_letters+string.digits)[x] for x in random.sample(range(0, 62), length)]) 
str = ''.join(random.sample(string.ascii_letters+string.digits, length))

str = ''.join(map(lambda xx:(hex(ord(xx))[2:]),os.urandom(16))) # length = 32