An expression like
````
output(count(x))

appears to be converted to a normalized form:

x := table(x, {cnt := count(group)})[1]);
extractresult(dataset(x), x.cnt);

Rather than

x := table(x, {cnt := count(group)}));
setresult(x[1].cnt);

However there are various optimizations that spot the second form as a scalar aggregate. It might be much better to generate the second form, and then convert it to use extract much later in the processing (just before the graph is resourced).

@Shamser Ahmed