If you want to know whether something is a table capable of doing some known method you can generally do this:
``````lua
if 'table' == type(thing) then
if 'function' == type(thing.includes) then
io.stderr:write"A thing has a method 'includes'\n'"
end
end
``````
In the context of Lua filters you would typically put the above code in a dummy global Pandoc function and run the "filter" with just
``````commandline
pandoc -L dummy.lua
<Ctrl-D>
``````
and if the test is successful you will see the message.
On Windows you would press <Ctrl-Z> rather than <Ctrl-D>.
--
Better --help|less than helpless