lambda - Advanced C++ multiple parentheses

I'm reviewing a sample program code and found this
line:

auto prerequisite
            =
            task([](){});

What
is the meaning of those combined parentheses
([](){})

I'm a cpp
programmer but do not know advance cpp (c11+) which this Microsoft example is written
at. Googling didn't help, and I don't know the name of those
operators.

itemprop="text">

class="normal">Answer

[](){} is a href="https://en.cppreference.com/w/cpp/language/lambda" rel="noreferrer">lambda
expression that creates a function object that has non-zero size and does
nothing.

This is probably to avoid checking
whether prerequisite is valid/exists - it is always valid, but
may do nothing.