Can we reduce the size of file generated with empty_df.to_hdf() below 2MB?
I store my dataframes on disk with `df.to_hdf()`, but to my surprise, even for an empty dataframe the resulting file size is 2MB. Is there a way to make it smaller? Thanks!
```python
import pandas as pd
empty_df = pd.DataFrame()
empty_df.to_hdf('empty_df.hdf', 'data')
```

NB: Versions tested: Pandas 0.21.1, Pandas 1.03.