import string
import random


def random_str(length: int = 10, unique: str = '') -> str:
    """Generate a random string

    Args:
        length (int): Optional. The length of the generated str.
        unique (str): Optional. Add a unique str to the end of the generated str
            (if you want to make sure that it's unique).

    Returns:
        str: randomly generated string
    """
    letters = string.ascii_lowercase
    return ''.join(random.choice(letters) for i in range(length)) + unique