code: func GetMetadataFromBlockOrPanic(block *cb.Block, index cb.BlockMetadataIndex) *cb.Metadata {
  	md, err := GetMetadataFromBlock(block, index)
  	if err != nil {
  		panic(err)
  	}
  	return md
  }
docs: // GetMetadataFromBlockOrPanic retrieves metadata at the specified index, or
  // panics on error