code: func (w *DeleteWALEntry) Encode(dst []byte) ([]byte, error) {
  	sz := w.MarshalSize()
  
  	if len(dst) < sz {
  		dst = make([]byte, sz)
  	}
  
  	var n int
  	for _, k := range w.Keys {
  		n += copy(dst[n:], k)
  		n += copy(dst[n:], "\n")
  	}
  
  	// We return n-1 to strip off the last newline so that unmarshalling the value
  	// does not produce an empty string
  	return []byte(dst[:n-1]), nil
  }
docs: // Encode converts the DeleteWALEntry into a byte slice, appending to dst.