How to use Rails date helper methods outside of Rails?

I am converting some Rails controller code to be generic Ruby code. I came across this:

expiration_date = 1.hours.from_now.utc.strftime('%Y-%m-%dT%H:%M:%S.000Z')

...and realized this is not standard Ruby. I get this error message:

undefined method `hours' for 1:Fixnum (NoMethodError)

How can I convert this to standard Ruby, or require/include the necessary libraries to make this work?

Solution:

require 'rubygems'
require 'active_support/core_ext/numeric/time'

ruby-on-rails ruby date

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