DSL EXPRESSION:
end{@mean=@sum/@count; emitf @mean}; begin {@count=0; @sum=0.0}; @count=@count+1; @sum=@sum+$x


AST:
* statement block
    * end block
        * statement block
            * assignment "="
                * direct oosvar value "mean"
                * operator "/"
                    * direct oosvar value "sum"
                    * direct oosvar value "count"
            * emitf statement "emitf"
                * emittable list
                    * direct oosvar value "mean"
                * no-op
    * begin block
        * statement block
            * assignment "="
                * direct oosvar value "count"
                * int literal "0"
            * assignment "="
                * direct oosvar value "sum"
                * float literal "0.0"
    * assignment "="
        * direct oosvar value "count"
        * operator "+"
            * direct oosvar value "count"
            * int literal "1"
    * assignment "="
        * direct oosvar value "sum"
        * operator "+"
            * direct oosvar value "sum"
            * direct field value "x"

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

mean
0.45362938403357633
