module TrueFalseComparison
  def <=>(other)
    return nil if ![TrueClass, FalseClass].include?(other.class)

    self.is_a?(FalseClass) ? (other.is_a?(TrueClass) ? -1 : 0) : (other.is_a?(FalseClass) ? 1 : 0)
  end
end
TrueClass.send(:include, TrueFalseComparison)
FalseClass.send(:include, TrueFalseComparison)

>> true <=> false
=> 1
>> true <=> true
=> 0
>> true <=> 'asdf'
=> nil
>> false <=> false
=> 0
>> false <=> true
=> -1
>> false <=> 'asdf'
=> nil
>> [1,2,3,4].sort_by { |n| n==3 }
=> [1, 2, 4, 3]