import re


def validate_string(password_string):
    """
    Performs a number of checks to see
    if a string can be a valid password
    """
    if len(password_string) < 8:
        message = "Password must contain atleat 8 characters."
        return (message, False)
    elif re.search('[0-9]', password_string) is None:
        message = "Password must contain atleast one number"
        return (message, False)
    else:
        message = None
        return (message, True)