Get size of a file/directory in bytes.

    Will return None if path does not exist or cannot be accessed.

def raw_filesize(path):
    # type: (str) -> Optional[int]
    """ Get size of a file/directory in bytes.

    Will return None if path does not exist or cannot be accessed.
    """
    with open('/dev/null', 'w') as devnull:
        status, output = shell("du", "-bs", path, raise_on_status=False,
                               stderr=devnull)
    if status != 0:
        return None
    # output is: <size>\t<path>\n
    return int(output.split("\t", 1)[0])