final protected static function normalizeColumnList($list, $default = null)
    {
        $result = [];
        foreach ($list as $key => $value) {
            if (is_int($key)) {
                $result[$value] = $default;
            } else {
                $result[$key] = $value;
            }
        }
        return $result;
    }
final protected static function normalizeColumnList($list, $default = null)
    {
        $result = [];
        foreach ($list as $key => $value) {
            if (is_int($key)) {
                $result[$value] = $default;
            } else {
                $result[$key] = $value;
            }
        }
        return $result;
    }
final protected static function normalizeColumnList ( $ list , $ default = null ) { $ result = [ ] ; foreach ( $ list as $ key => $ value ) { if ( is_int ( $ key ) ) { $ result [ $ value ] = $ default ; } else { $ result [ $ key ] = $ value ; } } return $ result ; }
Normalize column lists

EXAMPLE:
$list = [
'column_a',
'column_b' => value,
];

return [
'column_a' => $default,
'column_b' => value,
];

NOTE:
- Columns can not contain only numbers

@param mixed[] $list    Array to be normalized
@param mixed   $default Value to columns listed as value

@return mixed[]
Normalize column lists