some experimental use of Rapids.
can't seem to figure out the function def grammar
test_rapids_row_range.py is an experiment with using light python functions, nested, to build up and execute Rapids strings.
e.g.
    resultExec, result = rExec(rAssign(hex_key_i, rFrame(hex_key, rColon('#1', rNum(rowCount-10)), None)))

I think I avoid simple grammar errors with that, since "nested function calls with comma-separated params" is an easy to write/read grammar.
and you can stick arbitrary python in any parameter.
The above sends this ast= to h2o (and returns the json object, and any single value scalar or key result)

    (= !cA_0 ([ $cA (: #1 #999990) "null"))
(changed to start with x..)
test_rapids_row_range.py is an experiment with using light python functions, nested, to build up and execute Rapids strings.

    resultExec, result = xExec(xAssign(hex_key_i, xFrame(hex_key, xColon('#1', xNum(xowCount-10)), None)))

I think I avoid simple grammar errors with that, since "nested function calls with comma-separated params" is an easy to write/read grammar.
and you can stick arbitrary python in any parameter, as long as you get a good final result that matches the parameter def.
The above sends this ast= to h2o (and returns the json object, and any single value scalar or key result)

    (= !cA_0 ([ $cA (: #1 #999990) "null"))