## Explanation

Export a function from assets controller to fetch token exchange rates.

This function will be used by extension to compute user token fiat
amount and display it on the import token modal confirmation page.

## References

* Fixes
[#12345](https://consensyssoftware.atlassian.net/browse/MMASSETS-88)
* Related to
[#67890](MetaMask/metamask-extension#22263)

## Changelog

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### `@metamask/assets-controllers`

- **<CATEGORY>**: Updated `assetsUtil `file to export
`fetchAndMapExchangeRates `function

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've highlighted breaking changes using the "BREAKING" category
above as appropriate