一个python高强度密码生成器，可以指定要生成的密码长度

from os import urandom 
from random import choice 
  
char_set = {'small': 'abcdefghijklmnopqrstuvwxyz', 
             'nums': '0123456789', 
             'big': 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 
             'special': '^!\$%&/()=?{[]}+~#-_.:,;<>|\\' 
            } 
  
  
def generate_pass(length=21): 
    """Function to generate a password""" 
  
    password = [] 
  
    while len(password) < length: 
        key = choice(char_set.keys()) 
        a_char = urandom(1) 
        if a_char in char_set[key]: 
            if check_prev_char(password, char_set[key]): 
                continue 
            else: 
                password.append(a_char) 
    return ''.join(password) 
  
  
def check_prev_char(password, current_char_set): 
    """Function to ensure that there are no consecutive 
    UPPERCASE/lowercase/numbers/special-characters.""" 
  
    index = len(password) 
    if index == 0: 
        return False 
    else: 
        prev_char = password[index - 1] 
        if prev_char in current_char_set: 
            return True 
        else: 
            return False 
  
if __name__ == '__main__': 
    print generate_pass()