DataFrame.to_dict not using python types
I have a dataframe that I need to convert to a `dict` and add it to another `dict` which is converted to json in the end. Unfortunately since `.to_dict()` does not use standard python types I get the following:

```TypeError: Object of type 'int32' is not JSON serializable```

My code is something like the following:
```python
output = {
    'foo': 1,
    'bar': 2
}
...
df = ...
output['baz'] = df.to_dict()

send(json.dumps(output))
```

Using `dumps` results in the above error. This is related to https://github.com/pandas-dev/pandas/issues/13258 where an 'easy way' was mentioned but I'm not sure what it is.

Would appreciate any help