public function escape($identifier): string {
        if ($identifier instanceof Literal) {
            return $identifier->getValue($this);
        }
        return '`'.str_replace('`', '``', $identifier).'`';
    }
public function escape($identifier): string {
        if ($identifier instanceof Literal) {
            return $identifier->getValue($this);
        }
        return '`'.str_replace('`', '``', $identifier).'`';
    }
public function escape ( $ identifier ) : string { if ( $ identifier instanceof Literal ) { return $ identifier -> getValue ( $ this ) ; } return '`' . str_replace ( '`' , '``' , $ identifier ) . '`' ; }
Escape an identifier.

@param string|Literal $identifier The identifier to escape.
@return string Returns the field properly escaped.
Escape an identifier .