Illuminate\Database\Eloquent\Model::getCreatedAtColumn PHP Method

    public function getCreatedAtColumn()
    {
        return static::CREATED_AT;
    }

 /**
  * Get the name of the "created at" column.
  *
  * @return string
  */
 public function createdAt()
 {
     return $this->parent->getCreatedAtColumn();
 }