Im trying to create a empty dataframe with 3 columns: `movieId`, `title` and `predicted_rating`.

This is what I have so far:

```
column_names = ["movieId", "title", "predicted_rating"]

return_df = pd.DataFrame(columns=column_names)

return_df.append({"movieId":1,"title":2,"predicted_rating":3}, ignore_index=True)

```

When I run this code and print `return_df` the df has the column names but no row. The code to append a new row is from another question so I think the problem is the way i'm making the empty dataframe.