Add stamp in nPython Executor

nsql/nsql_exec_python.py

@@ -16,7 +16,7 @@ class NPythonExecutor(object):
         self.new_col_name_id = 0
         self.qa_model = OpenAIQAModel(args, keys)
 
-    def nsql_exec(self, nsql: str, db: pd.DataFrame, verbose=True):
+    def nsql_exec(self, stamp, nsql: str, db: pd.DataFrame, verbose=True):
         # Add import part
         import_part = """import sys
 import random