# Demo 1 — Round-Trip DOCX Modifier

Opens an existing DOCX, reports its current margins, headers, footers and
document properties, modifies them, and saves to a new file.

**What it demonstrates:** All read and write operations on an existing document.

```
python demo1_roundtrip.py input.docx output.docx
python demo1_roundtrip.py input.docx output.docx SSDX-XXXX-XXXX-XXXX-XXXX
```
