src/Primitive/Container/Container.php
public function filter(callable $function, $recursive = false)
    {
        if ( ! $this->getBoolable($recursive))
        {
            return new static(array_filter($this->items, $function));
        }

        return new static($this->filterRecursive($function, $this->items));
    }
public function filter(callable $function, $recursive = false)
    {
        if ( ! $this->getBoolable($recursive))
        {
            return new static(array_filter($this->items, $function));
        }

        return new static($this->filterRecursive($function, $this->items));
    }
Return filtered Container.
You can specify recursive filter with the second argument.

@param callable $function
@param bool|BooleanContract $recursive
@return Container