docs: def isConnected(self, signal, slot):
          """
          Returns if the given signal is connected to the inputted slot.
          
          :param      signal | <variant>
                      slot   | <callable>
          
          :return     <bool> | is connected
          """
          sig_calls = self._callbacks.get(signal, [])
          for callback in sig_calls:
              if callback == slot:
                  return True
          return False