Rubinius does not recognize methods in the File class

I have a project that has alot of file manipulation. I am trying out Rubinius because I need to be able to compile the code. When I try to run code that includes

if Dir.exist?(file_path)

I get this error:

NoMethodError开发者_如何转开发: undefined method `exist?' on Dir (Class)

Is there something I need to include to get this recognized? Btw, I have also tried Dir.exists? since it is an alias, and that didn't work either. Is the issue that this method didn't exist in 1.8.7? I can't seem to find a list of

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The issue was that Rubinius is using 1.8.7 and this method didn't exist then.