# Libtmux.Query.one_or_none

- **Module:** Libtmux
- **Package:** libtmux
- **Language:** OCaml
- **Kind:** function
- **Source:** https://github.com/libtmux/libtmux-ocaml/blob/205dfda49742592b479247049d186956e4a4cfe9/lib/libtmux.mli#L706
- **Public owner:** Libtmux
- **Page:** https://libtmux.org/en/ocaml/latest/reference/libtmux-query-one_or_none/

```
val one_or_none : 'a Seq.t -> ('a option, Cardinality.error) result
```

As [`exactly_one`](/en/ocaml/latest/reference/libtmux-query-exactly_one/), with `Ok None` for an empty sequence. Order and duplicate entries count toward cardinality; values are not deduplicated.

## Parameters

- `arg1` (`'a Seq.t`)

## Guides

Pages that discuss `one_or_none`.

- [Query captured data](/en/ocaml/latest/guides/queries/)