code: 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),
  	}
  }
docs: // GxCoord returns a new gx:Coord element.