select method
Implementation
void select(int start, int end, {
TextAffinity affinity = TextAffinity.downstream
}) {
final sel = TextSelection(baseOffset: start, extentOffset: end, affinity: affinity);
if(!controller.isSelectionWithinTextBounds(sel)) {
throw AFException("Text selection from $start to $end is out of range for ${controller.text}");
}
controller.selection = sel;
}