def __add_left_0(stri: str, target_length: int) -> str:
    """
    Adds left 0s to the current string until the target length is reached

    Parameters
    ----------------
    stri
        String
    target_length
        Target length

    Returns
    ----------------
    stri
        Revised string
    """
    while len(stri) < target_length:
        stri = "0" + stri
    return stri