Doctrine\MongoDB\Aggregation\Stage::lookup PHP Method

Performs a left outer join to an unsharded collection in the same database to filter in documents from the “joined” collection for processing.

See also: https://docs.mongodb.org/manual/reference/operator/aggregation/lookup/

public lookup ( string $from ) : Doctrine\MongoDB\Aggregation\Stage\Lookup
$from	string
return	Doctrine\MongoDB\Aggregation\Stage\Lookup

    public function lookup($from)
    {
        return $this->builder->lookup($from);
    }

Stage