Remove unneeded initialization

freqtrade/arguments.py

@@ -517,7 +517,8 @@ class Arguments(object):
         )
         parser.add_argument(
             '--trade-source',
-            help='Specify the source for trades (Can be DB or file (backtest file)) Default: %(default)s',
+            help='Specify the source for trades (Can be DB or file (backtest file)) '
+                 'Default: %(default)s',
             dest='trade_source',
             default="file",
             choices=["DB", "file"]

scripts/plot_dataframe.py

@@ -124,7 +124,6 @@ def analyse_and_plot_pairs(config: Dict[str, Any]):
         tickers = {}
         tickers[pair] = data
         dataframe = generate_dataframe(strategy, tickers, pair)
-        trades = None
         if config["trade_source"] == "DB":
             trades = load_trades_from_db(config["db_url"])
         elif config["trade_source"] == "file":