# XO0703: effect declared in `uses` is never performed

Reported by `xo vet` as a warning, never by `xo check`. Declaring more effects than the body performs is allowed, for example to keep an interface or a `pub` API stable while its implementation changes (core 6.2). Unless that is the intent, the extra effect overstates what the function can do and forces callers to declare it too. Remove it, or keep it deliberately.

## Example

```xo
pub fn now(c: Clock) -> Time uses clock, net {
  c.now()
}
```

## Fix

```xo
pub fn now(c: Clock) -> Time uses clock {
  c.now()
}
```

Run `xo explain XO0703` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).