Where do you test syntax of D regexp online?

[Suliman via Digitalmars-d-learn]

On Friday, 10 March 2017 at 14:36:48 UTC, Suliman wrote:
> On Thursday, 9 March 2017 at 16:47:18 UTC, Adam D. Ruppe wrote:
>> On Thursday, 9 March 2017 at 16:40:13 UTC, Suliman wrote:
>>> How should I write to file result without \r\n\ symbols?
>>>
>>> auto x = content.matchFirst(bigCodeBlock);
>>>
>>> File f = File("foo.txt", "w");
>>> f.write(x);
>>
>> Just
>>
>> f.write(x[0]);
>>
>>
>> to write out the whole hit instead of the collection of 
>> references.
>
> What can be wrong with this regexp? 
> https://regex101.com/r/8e7nPL/3
> it's crush D compiler, and I can't find out why

I need simply select parts from one first-level # to another.

like:
#header
some text
and some code

^ first matching


#header2
some text2
and some code2

^ second matching