code: public void push(String symbol) {
          long now = System.currentTimeMillis();
          if (!symbol.equals(lastSymbol) || (now - lastActivity > interdigitInterval)) {            
              lastActivity = now;
              lastSymbol = symbol;
  
              detectorImpl.fireEvent(symbol);
          }
          else
              lastActivity=now;
      }
docs: Handles inter digit intervals.
  
  @param symbol received digit.