Zel autoclose functionality.

[zolyfarkas]

This functionality is similar with Golang defer, java Try with resources, but it will be simpler to use.

{
auto(close) a = new FileInputStream();
auto(close) b = new FileInputStream();

}

should be closed at the end of the block.

the more general differ pattern can be implemented as well:

{
a = new FileInputStream();
defer a.close();
...
}