public function index($columns, $name = null, $type = __FUNCTION__)
    {
        return $this->addIndex($type, $columns, $name);
    }
public function index($columns, $name = null, $type = __FUNCTION__)
    {
        return $this->addIndex($type, $columns, $name);
    }
public function index ( $ columns , $ name = null , $ type = __FUNCTION__ ) { return $ this -> addIndex ( $ type , $ columns , $ name ) ; }
Specify an index for the table.

@param  string|array $columns
@param  string|null  $name
@param  string       $type Type of index

@return \Neutrino\Database\Schema\Definition
Specify an index for the table .