#nop 两个字符串参数，其中一个比另一个多包含了一个子串，本函数可返回该子串（即任务信息）;
#func {diff} {
    #local str1 {%1};
    #local str2 {%2};

    #list str1 {tokenize} {$str1};
    #list str2 {tokenize} {$str2};

    #local size1 {&str1[]}; 
    #local size2 {&str2[]}; 

    #if { $size1 < $size2 } {
        #local tmp      {$str1};
        #local str1     {$str2};
        #local str2     {$tmp};
        #local tmp      {$size1};
        #local size1    {$size2};
        #local size2    {$tmp};
    };

    #local idx {};
    #loop {1} {$size2} {idx} {
        #local ch1 {$str1[$idx]};
        #local ch2 {$str2[$idx]};
        #if { "$ch1" != "$ch2" } {
            #break;
        };
    };

    #local begin    {$idx};
    #local end      {};
    #math  end      {$size1 - $size2 + $begin - 1};
    #local diff     {};
    #loop {$begin} {$end} {idx} {
        #local ch {$str1[$idx]};
        #cat diff {$ch};
    };

    #return {$diff};
};

/*
#alias {diff.test} {
    #local str1 {洞中无丝毫光亮，脚华山的练功房下平整，便似走在石板路上一般。};
    #local str2 {洞中无丝毫光亮，脚下平整，便似走在石板路上一般。};
    #echo {STR1: $str1};
    #echo {STR2: $str2};
    #local diff {@diff{{$str1};{$str2}}};
    #nop 会得到「华山的练功房」
    #echo {DIFF: $diff};
};
*/