# Sequence.oneOrNil(_:)

- **Module:** Sequence
- **Package:** libtmux-swift
- **Language:** Swift
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-swift/blob/254f8b2be7eb60cacc3ffcb3ea8e456784f582df/Sources/LibTmux/FilterExpr.swift#L366
- **Page:** https://libtmux.org/en/swift/latest/reference/sequence-oneornil(_-)/

```
Sequence.oneOrNil(_:)(expression: FilterExpr<Element>) -> Self.Element?
```

The one element the filter matches, or `nil` if none did.

Only ambiguity is an error here; absence is an ordinary answer.

## Raises

- `FilterSelectionError`