DSL EXPRESSION:
$z = ENV["HOME"]


AST:
"block" [tt:block] [nt:StatementBlock]
    "=" [tt:equals] [nt:Assignment]
        "$z" [tt:field_name] [nt:DirectFieldValue]
        "ENV" [tt:kw_env] [nt:EnvironmentVariable]
            ""HOME"" [tt:string_literal] [nt:string_literal]

