[Xml-compile] finding the nillable elements of a sequence type

[E R]

On Fri, Oct 19, 2012 at 4:21 PM, Mark Overmeer <mark at overmeer.net> wrote:
> * E R (pc88mxer at gmail.com) [121019 20:30]:
>> In a <sequence> type I would like to determine which fields are
>> nillable, and so I wrote the following code.
>
> From all the few dozen features, what is so special about nillable?

Really I'd like to know about the correctness of my each_element()
function. One of things it does is it traverses the type of any
<extension> nodes it finds. Am I using the XML::Compile API correctly?
Note how nillable() is defined in terms of each_element().