import random


def getRandomFileStr(characters: str = "abcdefghijklmnopqrstuvwxyz0123456789", minWidth: int = 4, maxWidth: int = 8):
    """
    Function to usea character set to generate a random string of desired width
    Args:
        characters: Series of char candidates
        minWidth: Min random width window of chars.
        maxWidth: Max random width window of chars.

    Returns: string of random chars.

    """
    seqLetters = ''
    seqSize = random.randint(minWidth, maxWidth)
    for _ in range(seqSize):
        randValue = random.randint(0, len(characters)-1)
        seqLetters += characters[randValue]
    return seqLetters