toggle method
Toggle put/pull the supplied values from the selection
Implementation
void toggle(List<S2Choice<T>> choices, {bool? pull}) {
if (pull == true) {
omit(choices);
} else if (pull == false) {
merge(choices);
} else {
if (hasAny(choices)) {
omit(choices);
} else {
merge(choices);
}
}
}