I have the following small code example:

```
std::function<bool()> isSet;

bool check() {
   bool tmp;
   return tmp;
}

std::function<bool()> isSet {
    return check();
}

```

This gives me the following error message

```
could not convert 'isSet()' from 'bool' to 'std::function<bool()>'

```

Can anyone explain why and how I to fix it?