func GxCoord(value Coordinate) *SimpleElement {
	return &SimpleElement{
		StartElement: xml.StartElement{
			Name: xml.Name{Local: "gx:coord"},
		},
		Value: strconv.FormatFloat(value.Lon, 'f', -1, 64) + " " +
			strconv.FormatFloat(value.Lat, 'f', -1, 64) + " " +
			strconv.FormatFloat(value.Alt, 'f', -1, 64),
	}
}
GxCoord returns a new gx:coord element.
package kml
import (
	"encoding/xml"
	"strconv"
)
const GxNamespace = "http://www.google.com/kml/ext/2.2"
type GxOptionName string
const (
	GxOptionNameHistoricalImagery GxOptionName = "historicalimagery"
	GxOptionNameStreetView        GxOptionName = "streetview"
	GxOptionNameSunlight          GxOptionName = "sunlight"
)
type GxAngle struct {
	Heading, Tilt, Roll float64
}
func GxAngles(value GxAngle) *SimpleElement {
	return &SimpleElement{
		StartElement: xml.StartElement{
			Name: xml.Name{Local: "gx:angles"},
		},
		Value: strconv.FormatFloat(value.Heading, 'f', -1, 64) + " " +
			strconv.FormatFloat(value.Tilt, 'f', -1, 64) + " " +
			strconv.FormatFloat(value.Roll, 'f', -1, 64),
	}
}