public function addSkillVersion(ChildSkillVersion $l)
    {
        if ($this->collSkillVersions === null) {
            $this->initSkillVersions();
            $this->collSkillVersionsPartial = true;
        }

        if (!$this->collSkillVersions->contains($l)) {
            $this->doAddSkillVersion($l);
        }

        return $this;
    }