Feat: init dataflow. (#9791)

### What problem does this PR solve?

#9790

Close #9782

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

deepdoc/parser/excel_parser.py

@@ -131,6 +131,12 @@ class RAGFlowExcelParser:
 
         return tb_chunks
 
+    def markdown(self, fnm):
+        import pandas as pd
+        file_like_object = BytesIO(fnm) if not isinstance(fnm, str) else fnm
+        df = pd.read_excel(file_like_object)
+        return df.to_markdown(index=False)
+
     def __call__(self, fnm):
         file_like_object = BytesIO(fnm) if not isinstance(fnm, str) else fnm
         wb = RAGFlowExcelParser._load_excel_to_workbook(file_like_object)