Why do the same work about 'IndexOfAny' and 'indexOf' function?

[bearophile via Digitalmars-d-learn]

FrankLike:

> But now I want to know in a string (like "hello.exe" or 
> "hello.a",or "hello.dll" or "hello.lib" ) whether contains any 
> of them: ["exe","dll","a","lib"].

Seems this:
http://rosettacode.org/wiki/File_extension_is_in_extensions_list#D

Bye,
bearophile