Merge with develop

freqtrade/arguments.py

@@ -72,7 +72,7 @@ class Arguments(object):
         self.parser.add_argument(
             '--version',
             action='version',
-            version='%(prog)s {}'.format(__version__),
+            version=f'%(prog)s {__version__}'
         )
         self.parser.add_argument(
             '-c', '--config',
@@ -165,6 +165,11 @@ class Arguments(object):
 
     @staticmethod
     def optimizer_shared_options(parser: argparse.ArgumentParser) -> None:
+        """
+        Parses given common arguments for Backtesting and Hyperopt scripts.
+        :param parser:
+        :return:
+        """
         parser.add_argument(
             '-i', '--ticker-interval',
             help='specify ticker interval (1m, 5m, 30m, 1h, 1d)',
@@ -243,7 +248,7 @@ class Arguments(object):
         :return: Start and End range period
         """
         if text is None:
-            return TimeRange()
+            return TimeRange(None, None, 0, 0)
         syntax = [(r'^-(\d{8})$', (None, 'date')),
                   (r'^(\d{8})-$', ('date', None)),
                   (r'^(\d{8})-(\d{8})$', ('date', 'date')),
@@ -296,28 +301,34 @@ class Arguments(object):
             '--pairs-file',
             help='File containing a list of pairs to download',
             dest='pairs_file',
-            default=None
+            default=None,
+            metavar='PATH',
         )
 
         self.parser.add_argument(
             '--export',
             help='Export files to given dir',
             dest='export',
-            default=None)
+            default=None,
+            metavar='PATH',
+        )
 
         self.parser.add_argument(
             '--days',
             help='Download data for number of days',
             dest='days',
             type=int,
-            default=None)
+            metavar='INT',
+            default=None
+        )
 
         self.parser.add_argument(
             '--exchange',
             help='Exchange name (default: %(default)s)',
             dest='exchange',
             type=str,
-            default='bittrex')
+            default='bittrex'
+        )
 
         self.parser.add_argument(
             '-t', '--timeframes',