> You will need your `API URL` and your `API token` in order to connect the Client SDK to you Unleash instance. You can find this information in the “Admin” section Unleash management UI. [Read more](../user_guide/api-token)
- Must accept the fature name and context as an argument.
- Client will evaluate the fallback function only if exception occurs when calling the `is_enabled()` method i.e. feature flag not found or other general exception.
- If both a `default_value` and `fallback_function` are supplied, client will define the default value by `OR`ing the default value and the output of the fallback function.
### Getting a variant
Checking for a variant:
```python
context = {'userId': '2'} # Context must have userId, sessionId, or remoteAddr. If none are present, distribution will be random.