#rustlang oops wow the https://docs.rs/tokio/1.43.0/tokio/io/trait.AsyncWrite.html#method.poll_write_vectored default fallback impl is extremely un-POLA

> Data is copied from each buffer in order […] must behave as a call to write with the buffers concatenated
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> The default implementation calls poll_write with either the first nonempty buffer provided […]