using constants instead of stripping the string

freqtrade/freqtradebot.py

@@ -140,7 +140,7 @@ class FreqtradeBot(object):
         # TODO: Add tests for this and the async stuff above
          
         ticker_interval = self.strategy.ticker_interval
-        interval_in_seconds = int(ticker_interval[:-1]) * 60
+        interval_in_seconds = constants.TICKER_INTERVAL_MINUTES[ticker_interval] * 60
 
         should_not_update = ((self._klines_last_fetched_time + interval_in_seconds +1) > round(time.time()))