Added DataVersion str() operator. (#312)

# Changes
- Added simplified `str()` operator to `DataVersion` (e.g., "6.7")

# Fixes
- Fixed CSV-style command line arguments appending to the default value unexpectedly

python/fusion_engine_client/messages/configuration.py

@@ -1601,6 +1601,9 @@ class DataVersion(NamedTuple):
     major: int
     minor: int
 
+    def __str__(self):
+        return f'{self.major}.{self.minor}'
+
 
 _DataVersionConstructRaw = Struct(
     Padding(1),

python/fusion_engine_client/utils/argument_parser.py

@@ -176,6 +176,8 @@ def __call__(self, parser, namespace, values, option_string=None):
         result = getattr(namespace, self.dest)
         if result is None:
             result = []
+        elif result is self.default:
+            result = []
         result.extend(flattened_values)
         setattr(namespace, self.dest, result)