code: func (t *TraceID) UnmarshalJSON(traceID []byte) error {
  	if len(traceID) < 3 {
  		return ErrValidTraceIDRequired
  	}
  	// A valid JSON string is encoded wrapped in double quotes. We need to trim
  	// these before converting the hex payload.
  	tID, err := TraceIDFromHex(string(traceID[1 : len(traceID)-1]))
  	if err != nil {
  		return err
  	}
  	*t = tID
  	return nil
  }
docs: // UnmarshalJSON custom JSON deserializer to retrieve the traceID from the hex
  // encoded representation.