private function getTopologyGroup(string $char): string
    {
        $groups = $this->chars;

        if (\strpos($groups[0], $char) !== false) {
            return 'u';
        }

        if (\strpos($groups[1], $char) !== false) {
            return 'l';
        }

        if (\strpos($groups[2], $char) !== false) {
            return 'd';
        }

        if (\strpos($groups[3], $char) !== false) {
            return 's';
        }

        throw new InvalidArgumentException('Out of group character provided.');
    }
private function getTopologyGroup(string $char): string
    {
        $groups = $this->chars;

        if (\strpos($groups[0], $char) !== false) {
            return 'u';
        }

        if (\strpos($groups[1], $char) !== false) {
            return 'l';
        }

        if (\strpos($groups[2], $char) !== false) {
            return 'd';
        }

        if (\strpos($groups[3], $char) !== false) {
            return 's';
        }

        throw new InvalidArgumentException('Out of group character provided.');
    }
private function getTopologyGroup ( string $ char ) : string { $ groups = $ this -> chars ; if ( \ strpos ( $ groups [ 0 ] , $ char ) !== false ) { return 'u' ; } if ( \ strpos ( $ groups [ 1 ] , $ char ) !== false ) { return 'l' ; } if ( \ strpos ( $ groups [ 2 ] , $ char ) !== false ) { return 'd' ; } if ( \ strpos ( $ groups [ 3 ] , $ char ) !== false ) { return 's' ; } throw new InvalidArgumentException ( 'Out of group character provided.' ) ; }
Return topology group for the given char.

@param string $char

@return string

@throws InvalidArgumentException If char provided isn't inside any group
Return topology group for the given char .