[Frontend] Add FlexibleArgumentParser to support both underscore and dash in names (#5718)

examples/tensorize_vllm_model.py

@@ -9,6 +9,7 @@ from vllm.engine.arg_utils import EngineArgs
 from vllm.model_executor.model_loader.tensorizer import (TensorizerArgs,
                                                          TensorizerConfig,
                                                          tensorize_vllm_model)
+from vllm.utils import FlexibleArgumentParser
 
 # yapf conflicts with isort for this docstring
 # yapf: disable
@@ -96,7 +97,7 @@ deserialization in this example script, although `--tensorizer-uri` and
 
 
 def parse_args():
-    parser = argparse.ArgumentParser(
+    parser = FlexibleArgumentParser(
         description="An example script that can be used to serialize and "
         "deserialize vLLM models. These models "
         "can be loaded using tensorizer directly to the GPU "