deserialize method
Deserializes the FML template elements, attributes and children
Implementation
@override
void deserialize(XmlElement xml) {
// deserialize
super.deserialize(xml);
value = Xml.get(node: xml, tag: 'value');
language = Xml.get(node: xml, tag: 'language')?.toLowerCase().trim();
theme = Xml.get(node: xml, tag: 'theme');
}