Helper param as array(list)

Hello!
I do not understand how i can use list as param in helper?
So i have some helper
ex:

```
$this->_dust->helpers['print_r'] = function...
~~template.dust~~
{@print_r dump=... /}
```

How i can transmit into the dump list|array ?

`dump[1]="100"`
`dump["key"]="100"`
`dump[]="100"`
`dump.key="100"`
`dump=["key":data.reference]`

I try it all. Please help. I cant find any ex. about it.
