reader

type GPX struct {
	Tracks []struct {
		Segments []struct {
			Points []GPXTrkPoint `xml:"trkpt"`
		} `xml:"trkseg"`
	} `xml:"trk"`
}

type GPXExtension struct {
	XMLName xml.Name
	Value   float64 `xml:",chardata"`
}

type GPXExtensionSet struct {
	Children []GPXExtension `xml:",any"`
}

type GPXTrkPoint struct {
	Lat        float64         `xml:"lat,attr"`
	Lon        float64         `xml:"lon,attr"`
	Time       time.Time       `xml:"time"`
	Extensions GPXExtensionSet `xml:"extensions"`
}