class Hash
  # Return a hash that includes everything but the given keys. This is useful for
  # limiting a set of parameters to everything but a few known toggles:
  #
  #   @person.update(params[:person].except(:admin))
  def except(*keys)
    dup.except!(*keys)
  end

  # Replaces the hash without the given keys.
  def except!(*keys)
    keys.each { |key| delete(key) }
    self
  end
end