DSL EXPRESSION:
begin{@rsum = 0}; @rsum = @rsum + $x; $rsum = @rsum


AST:
* statement block
    * begin block
        * statement block
            * assignment "="
                * direct oosvar value "rsum"
                * int literal "0"
    * assignment "="
        * direct oosvar value "rsum"
        * operator "+"
            * direct oosvar value "rsum"
            * direct field value "x"
    * assignment "="
        * direct field value "rsum"
        * direct oosvar value "rsum"

a   b   i  x                   y                   rsum
pan pan 1  0.3467901443380824  0.7268028627434533  0.3467901443380824
eks pan 2  0.7586799647899636  0.5221511083334797  1.105470109128046
wye wye 3  0.20460330576630303 0.33831852551664776 1.3100734148943491
eks wye 4  0.38139939387114097 0.13418874328430463 1.6914728087654902
wye pan 5  0.5732889198020006  0.8636244699032729  2.264761728567491
zee pan 6  0.5271261600918548  0.49322128674835697 2.7918878886593457
eks zee 7  0.6117840605678454  0.1878849191181694  3.403671949227191
zee wye 8  0.5985540091064224  0.976181385699006   4.0022259583336135
hat wye 9  0.03144187646093577 0.7495507603507059  4.033667834794549
pan wye 10 0.5026260055412137  0.9526183602969864  4.536293840335763
