class Range  
  def intersect(other)  
    raise ArgumentError, 'value must be a Range' unless other.kind_of?(Range)  

    new_min = self.cover?(other.min) ? other.min : other.cover?(min) ? min : nil  
    new_max = self.cover?(other.max) ? other.max : other.cover?(max) ? max : nil  

    new_min && new_max ? new_min..new_max : nil  
  end  
  alias_method :intersection, :intersect
  alias_method :&, :intersection  
end