src/Schema/AbstractIndex.php
public function columns($columns): AbstractIndex
    {
        if (!is_array($columns)) {
            $columns = func_get_args();
        }

        $this->columns = $columns;

        return $this;
    }
public function columns($columns): AbstractIndex
    {
        if (!is_array($columns)) {
            $columns = func_get_args();
        }

        $this->columns = $columns;

        return $this;
    }
public function columns ( $ columns ) : AbstractIndex { if ( ! is_array ( $ columns ) ) { $ columns = func_get_args ( ) ; } $ this -> columns = $ columns ; return $ this ; }
Change set of index forming columns. Method must support both array and string parameters.

Example:
$index->columns('key');
$index->columns('key', 'key2');
$index->columns(['key', 'key2']);

@param string|array $columns Columns array or comma separated list of parameters.
@return self
Change set of index forming columns . Method must support both array and string parameters .