Added missing write(true) option.
Added missing write(true) option.

aakloxu/rust-by-example-cn,rust-lang-cn/rust-by-example-cn,jinyuanxie/rust-by-example-cn,rust-lang-cn/rust-by-example-cn,aakloxu/rust-by-example-cn,jinyuanxie/rust-by-example-cn