DSL EXPRESSION:
$x = 123. + 1e-2 / .2e3 + 1.e-3


AST:
* statement block
    * assignment "="
        * direct field value "x"
        * operator "+"
            * operator "+"
                * float literal "123."
                * operator "/"
                    * float literal "1e-2"
                    * float literal ".2e3"
            * float literal "1.e-3"

