rails/rails — pull request #11628 by Nerian (2013-07-27 19:26:37+00:00)
Title: Add Object#is_any_of?(option1, option2, ...)

Returns true if the object is equal to any of the
possibilities specified as parameters.

This simplifies:
if params[:subject] == :english || params[:subject] == :math || params[:subject] == :biology
...to:
params[:subject].is_any_of?(:english, :math, :biology)