import random
_list = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
_result = random.sample(_list, 6)
result = ''.join(_result)
print(result)

import random
_list = [chr(i) for i in range(48, 58)]
for upper, lower in zip(range(65, 90), range(97, 122)):
  _list.append(chr(upper))
  _list.append(chr(lower))
_result = random.sample(_list, 6)
result = ''.join(_result)
print(result)

import string
import random
_list = string.digits + string.ascii_letters
_result = random.sample(_list, 6)
 
result = ''.join(_result)
print(result)