toJson method
Implementation
Map<String, dynamic> toJson() {
final json = <String, dynamic>{};
if (letter != null) {
json[r'letter'] = letter;
}
if (index != null) {
json[r'index'] = index;
}
if (coefficient != null) {
json[r'coefficient'] = coefficient;
}
if (value != null) {
json[r'value'] = value;
}
return json;
}