code: func GrowByteSlice(arr []byte, minSize int) []byte {
  	assert2(minSize >= 0, "size must be positive (got %v): likely integer overflow?", minSize)
  	if cap(arr) < minSize {
  		newArr := make([]byte, Oversize(minSize, 1))
  		copy(newArr, arr)
  		return newArr[:minSize]
  	}
  	for len(arr) < minSize {
  		arr = append(arr, 0)
  	}
  	return arr
  }
docs: // L343