deserialize method
Deserializes the FML template elements, attributes and children
Implementation
@override
void deserialize(XmlElement xml)
{
// deserialize
super.deserialize(xml);
// properties
value = Xml.get(node: xml, tag: 'value');
onchange = Xml.get(node: xml, tag: 'onchange');
returnas = Xml.get(node: xml, tag: 'return');
}