==================
simple conditional expression
==================

foo = predicate() ? 1: 2

---

(config_file 
  (body 
    (attribute 
      (identifier) 
      (expression 
        (conditional 
          (expression (expr_term (function_call (identifier))))
          (expression (expr_term (literal_value (numeric_lit)))) 
          (expression (expr_term (literal_value (numeric_lit)))))))))