code: func (c *RawKVClient) Delete(key []byte) error {
  	start := time.Now()
  	defer func() { tikvRawkvCmdHistogramWithDelete.Observe(time.Since(start).Seconds()) }()
  
  	req := &tikvrpc.Request{
  		Type: tikvrpc.CmdRawDelete,
  		RawDelete: &kvrpcpb.RawDeleteRequest{
  			Key: key,
  		},
  	}
  	resp, _, err := c.sendReq(key, req, false)
  	if err != nil {
  		return errors.Trace(err)
  	}
  	cmdResp := resp.RawDelete
  	if cmdResp == nil {
  		return errors.Trace(ErrBodyMissing)
  	}
  	if cmdResp.GetError() != "" {
  		return errors.New(cmdResp.GetError())
  	}
  	return nil
  }
docs: // Delete deletes a key-value pair from TiKV.