Mostly Ruby question: How to change file modification time?

Does anyone know how to change file modification time with Ruby? I found
how to get last modification time, but dont know how to change it.

Thanks,
David

http://www.ruby-doc.org/core/classes/File.html#M000013

or

http://www.ruby-doc.org/core/classes/FileUtils.html#M001731

– Heikki

RDoc Documentation says
"
touch(list, options = {})

Options: noop verbose

Updates modification time (mtime) and access time (atime) of file(s) in
list. Files are created if they don’t exist.

FileUtils.touch ‘timestamp’
FileUtils.touch Dir.glob(‘*.c’); system ‘make’

[Source]
"