Organize server_args (#277)

python/sglang/api.py

@@ -43,6 +43,17 @@ def Runtime(*args, **kwargs):
 def set_default_backend(backend: BaseBackend):
     global_config.default_backend = backend
 
+def flush_cache(backend: BaseBackend = None):
+    backend = backend or global_config.default_backend
+    if backend is None:
+        return False
+    return backend.flush_cache()
+
+def get_server_args(backend: BaseBackend = None):
+    backend = backend or global_config.default_backend
+    if backend is None:
+        return None
+    return backend.get_server_args()
 
 def gen(
     name: Optional[str] = None,