import random
import string


def random_alphanumeric(length: int) -> str:
    """
    Returns random str with the combination of alphabetic and numeric

    :param length: char length
    :return: [0-9a-zA-Z]
    """

    letters = string.ascii_letters + string.digits
    random_str = ''.join(random.choice(letters) for i in range(length))
    return random_str