pub fn encode_block_meta(
        block_meta: &[BlockMeta],
        #[allow(clippy::ptr_arg)] // remove this allow after you finish
        buf: &mut Vec<u8>,
    ) {
        unimplemented!()
    }
Encode block meta to a buffer.
You may add extra fields to the buffer,
in order to help keep track of `first_key` when decoding from the same buffer in the future.
mini-lsm-starter/src/table.rs