src/IteratorPipeline/PipelineBuilder.php
public function setKeys(iterable $keys)
    {
        $combine = function ($values, $keys) {
            return new CombineIterator($keys, $values);
        };

        return $this->then($combine, i\iterable_to_array($keys));
    }
public function setKeys(iterable $keys)
    {
        $combine = function ($values, $keys) {
            return new CombineIterator($keys, $values);
        };

        return $this->then($combine, i\iterable_to_array($keys));
    }
Use another iterator as keys and the current iterator as values.

@param iterable $keys  Keys will be turned into an array.
@return static