PHP：仅将函数范围限制在当前文件中

Is there any way to limit the scope of non-class functions in a php file and making them the only accessible within the php file it is located in? Like how C can achieve this using static keyword with functions. In php static seems to be for classes only. I want to hide helper functions that should only be accessed by functions within the file. Thanks.Is there any way to limit the scope of non-clas