password_with_icontract.py

import icontract
from readonce import ReadOnce

def validate_password_length(password: str) -> bool:
    return len(password) > 7

class Password(ReadOnce):
    @icontract.ensure(lambda self: len(self) == 1, "Secret is missing")
    @icontract.require(
        lambda password: validate_password_length(password),
        "Password length should be more than 7",
    )
    def __init__(self, password: str) -> None:
        super().__init__()
        self.add_secret(password)