sub join_multi {
    die "not enough parameters for join_multi()" if @_ < 2;
    my $delim1 = shift;
    my $delim2 = shift;
    return @_ > 1 ? join $delim1, $_[0], join $delim2, @_[1 .. $#_]
         : @_     ? $_[0]
         : ''
         ;
    }

sub join_multi {
    die "not enough parameters for join_multi()" if @_ < 2;
    return @_  > 3 ? join $_[0], $_[2], join $_[1], @_[3 .. $#_]
         : @_ == 3 ? $_[2]
         : ''
         ;
    }

sub join_multi {
    die "not enough parameters for join_multi()" if @_ < 2;
    return
        join '',
        map { ('', $_[0], ($_[1]) x ($#_ - 2))[$_ - 2], $_[$_] }
        2 .. $#_
        ;
    }