code: public LHS toLHS( CallStack callstack, Interpreter interpreter)
          throws EvalError
      {
          // loosely typed map expression new {a=1, b=2} are treated
          // as non assignment (LHS) to retrieve Map.Entry key values
          // then wrapped in a MAP_ENTRY type LHS for value assignment.
          return (LHS) eval( interpreter.getStrictJava() || !isMapExpression,
                  callstack, interpreter );
      }
docs: Evaluate to a value object.