code: func Must(v interface{}, err error) interface{} {
  	if err != nil {
  		panic("copy error: " + err.Error())
  	}
  
  	return v
  }
docs: // Must is a helper that wraps a call to a function returning
  // (interface{}, error) and panics if the error is non-nil. It is intended
  // for use in variable initializations and should only be used when a copy
  // error should be a crashing case.