deregister method Null safety

void deregister(
  1. CalculatorButtonState s,
  2. String accelerator
)

Implementation

void deregister(CalculatorButtonState s, String accelerator) {
  for (final ch in Characters(accelerator)) {
    if (button[ch] == s) {
      // New mapping might have registered first
      button.remove(ch);
    }
  }
}