Double brackets?

Just encountered this bit of code:

if(iElement->getData().contains("someText") and iElement->getData()("someOtherText").toString() == "true")

What is boggling my mind is this part:

iElement->getData()("someOtherText").toString()

More precisely having: ()()

I haven't seen an overloader anywhere.

This is supposed to be C++ code by the way. Compiles and runs fine.

Could not find any information anywhere since I don't know what to even search for... Can someone please explain?