public function addSkill(ChildSkill $skill)
    {
        if ($this->collSkills === null) {
            $this->initSkills();
        }

        if (!$this->getSkills()->contains($skill)) {
            // only add it if the **same** object is not already associated
            $this->collSkills->push($skill);
            $this->doAddSkill($skill);
        }

        return $this;
    }