### The win module contains to get informations about the current
### window and groups in a windowed select statement

## Returns the **current** cardinality of a group by
## statement. When used without a group by it will
## return zero (0).
##
## > ```tremor
## > use std::win;
## > 
## > select { "group#{group[0]}": win::cardinality() }
## > from in
## > group by each([1, 2, 3, 4, 5]) into out;
## > ```
##
## Returns a `integer`
intrinsic fn cardinality(str) as win::cardinality;