securely getting the user's password

[Chick]

Hello,

I'm writing a security tool which requies wiping off the memory of
certain string after being used, which I've done by implementing it as
a mutable list as follow:

class secureStr:
    def __init__(self, str):
        self.__s = []
        for i in range(len(str)):
            self.s += str[i]

    def __str__(self):
        return "".join(self.__s)

    def wipe(self):
        for i in range(len(self.__s)):
            self.s[i] = '\x00'

    def __del__(self):
        self.wipe()

My question is how do I write a function to securely get the password
from user (in text mode)? If I do sth like

import getpass
securePass = secureStr(getpass,getpass())

doesn't that create an immediate string object that will stay in
memory?