# Solution 1: Runtime Checks

One solution to the problem would be to simply check the locked state and restrict methods to be only callable in the corrent locked state.

```rust
let mut pw = CredentialManager::new();
pw.set("foo", "bar")?; // this would bail with an error result
pw.unlock("pssst")?;
pw.unlock("pssst")?; // this would bail with an error result
pw.set("foo", "bar")?;
let val = pw.get("foo")?;
pw.lock()?;
pw.lock()?; // this would bail with an error result
```

## Caveats

Performing runtime checks on the state requires returning `Result` and also requires the check and handling of erroneous results on every call to the manager.