/**
  * Evaluates the expression.
  *
  * @param env the calling environment.
  *
  * @return the expression value.
  */
 public override Value evalAssignRef(Env env, Expr valueExpr)
 {
     // php/03mk
     // php/04ai
     return(_expr.evalArrayAssignRef(env, _index, valueExpr));
 }