  Statement_Ptr Expand::operator()(Declaration_Ptr d)
  {
    Block_Obj ab = d->block();
    String_Obj old_p = d->property();
    Expression_Obj prop = old_p->perform(&eval);
    String_Obj new_p = Cast<String>(prop);
    // we might get a color back
    if (!new_p) {
      std::string str(prop->to_string(ctx.c_options));
      new_p = SASS_MEMORY_NEW(String_Constant, old_p->pstate(), str);
    }
    Expression_Obj value = d->value();
    if (value) value = value->perform(&eval);
    Block_Obj bb = ab ? operator()(ab) : NULL;
    if (!bb) {
      if (!value || (value->is_invisible() && !d->is_important())) return 0;
    }
    Declaration_Ptr decl = SASS_MEMORY_NEW(Declaration,
                                        d->pstate(),
                                        new_p,
                                        value,
                                        d->is_important(),
                                        d->is_custom_property(),
                                        bb);
    decl->tabs(d->tabs());
    return decl;
  }
Unknown