class Sass::Selector::AbstractSequence

def _specificity(arr)
  min = 0
  max = 0
  arr.each do |m|
    next if m.is_a?(String)
    spec = m.specificity
    if spec.is_a?(Range)
      min += spec.begin
      max += spec.end
    else
      min += spec
      max += spec
    end
  end
  min == max ? min : (min..max)
end