Function runtime_with_regular_args 

pub fn runtime_with_regular_args(
    ignore_perm_errors_flag: bool,
    num_bytes: Option<usize>,
    filename_l: &str,
    filename_r: Option<&str>,
    hashes_filename: Option<&str>,
    writable: impl Write,
    num_vs: u8,
    progress: bool,
    find_file_sizes: bool,
) -> Result<i32, Error>

Return number of bytes