DSL EXPRESSION:
$new = ${a} . ${b}


AST:
"block" [tt:block] [nt:StatementBlock]
    "=" [tt:equals] [nt:Assignment]
        "$new" [tt:field_name] [nt:DirectFieldValue]
        "." [tt:op_dot] [nt:DotOperator]
            "${a}" [tt:braced_field_name] [nt:BracedFieldValue]
            "${b}" [tt:braced_field_name] [nt:BracedFieldValue]

a   b   i x          y          new
pan pan 1 0.34679014 0.72680286 panpan
eks pan 2 0.75867996 0.52215111 ekspan
wye wye 3 0.20460331 0.33831853 wyewye
eks wye 4 0.38139939 0.13418874 ekswye
