# ControlNotificationStream.filter(_:)

- **Module:** ControlNotificationStream
- **Package:** libtmux-swift
- **Language:** Swift
- **Kind:** method
- **Page:** https://libtmux.org/reference/swift/controlnotificationstream-filter(_-)/

```
ControlNotificationStream.filter(_:)(isIncluded: (Self.Element) async -> Bool) -> AsyncFilterSequence<Self>
```

Creates an asynchronous sequence that contains, in order, the elements of the base sequence that satisfy the given predicate.

In this example, an asynchronous sequence called `Counter` produces `Int`
values from `1` to `10`. The `filter(_:)` method returns `true` for even
values and `false` for odd values, thereby filtering out the odd values:

    let stream = Counter(howHigh: 10)
        .filter { $0 % 2 == 0 }
    for await number in stream {
        print(number, terminator: " ")
    }
    // Prints "2 4 6 8 10 "

- Parameter isIncluded: A closure that takes an element of the
  asynchronous sequence as its argument and returns a Boolean value
  that indicates whether to include the element in the filtered sequence.
- Returns: An asynchronous sequence that contains, in order, the elements
  of the base sequence that satisfy the given predicate.