Your unique API key. Note that each user has unique API keys for each of
Abstract’s APIs, so your Exchange Rates API key will not work for your IP
Geolocation API, for example.
The base currency used to get the latest exchange rate(s) for. Uses the ISO 4217 currency standard (e.g., USD for United States Dollars), like all currency parameters in this API.
The target currency or currencies to get the exchange rate of versus the base currency. Like the base parameters, any currency passed here follows the ISO 4217 standard. Note that unlinke the other endpoints, convert only accepts one target currency at a time.