Themr with pure functions

Does anyone have an example of using themr with pure function components vs. classes and how to provide a default theme and then override that theme from a parent container? I've searched through the readmes and issue log and I'm not finding anything solid as an example for this case.

Here's my thought on how it should work
```scss
/* defaultTheme.module.scss */
.button {
background-color: blue;
color: white;
}

```
```javascript
/* Button.js */
import React from 'react';
import PropTypes from 'prop-types';
import classNames from 'classnames';
import { themr } from 'react-css-themr';
import defaultTheme from './defaultTheme.module.scss';

const Button = ({ theme }) => {
const classes = classNames({ [theme.button]: true });
return Button;
};

Button.propTypes = {
theme: PropTypes.any
};

export default themr('Button', defaultTheme)(Button);

```
```scss
/* parentTheme.module.scss */
.button {
background-color: white;
color: blue;
}

```
```javascript
/* ParentContainer.js */
import React from 'react';
import { render } from 'react-dom';
import parentTheme from './parentTheme.module.scss';
import Button from './Button';

render(
,
document.getElementById('app');
);

```

Default theme seems to work fine and the button component displays the default styles no problem. However, nothing happens when the parent passes a theme down.

Start with the Button.js and ParentContainer.js examples in the issue, then inspect how themr combines the defaultTheme with a theme passed through the theme prop. Reproduce the example and verify that the parent theme replaces or overrides the default button styles; document the correct usage or identify the failing behavior.

Written by the indexing model from the issue text.