code: func (e Error) StackTraceString() string {
  	buf := new(bytes.Buffer)
  	for _, v := range e.Stack {
  		fmt.Fprintf(buf, "%s: %s\n\t%s\n", v.File, v.Number, v.Method)
  	}
  	return string(buf.Bytes())
  }
docs: // StackTraceString returns the stack trace in a string format.