# ControlNotificationStream.prefix(_:)

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

```
ControlNotificationStream.prefix(_:)(count: Int) -> AsyncPrefixSequence<Self>
```

Returns an asynchronous sequence, up to the specified maximum length, containing the initial elements of the base asynchronous sequence.

Use `prefix(_:)` to reduce the number of elements produced by the
asynchronous sequence.

In this example, an asynchronous sequence called `Counter` produces `Int`
values from `1` to `10`. The `prefix(_:)` method causes the modified
sequence to pass through the first six values, then end.

    for await number in Counter(howHigh: 10).prefix(6) {
        print(number, terminator: " ")
    }
    // Prints "1 2 3 4 5 6 "

If the count passed to `prefix(_:)` exceeds the number of elements in the
base sequence, the result contains all of the elements in the sequence.

- Parameter count: The maximum number of elements to return. The value of
  `count` must be greater than or equal to zero.
- Returns: An asynchronous sequence starting at the beginning of the
  base sequence with at most `count` elements.