phpstreams\Stream::all PHP Method

    public function all(callable $predicate = null)
    {
        if ($predicate === null) {
            $predicate = Functions::identity();
        }
        foreach ($this as $value) {
            if (!$predicate($value)) {
                return false;
            }
        }
        return true;
    }

 public function testAll()
 {
     $stream = new Stream([1, 4, 9, 16, 25]);
     // All these integers are truthy.
     $this->assertTrue($stream->all());
     // Not all of them are even.
     $this->assertFalse($stream->all(function ($value) {
         return $value % 2 == 0;
     }));
     // All of these are squares.
     $this->assertTrue($stream->all(function ($value) {
         $root = round(sqrt($value));
         return $root * $root == $value;
     }));
 }