class Differ::Diff

def delete(*str)
  return if str.empty?
  if @raw.last.is_a? Change
    change = @raw.pop
    if change.insert? && @raw.last
      @raw.last << sep if change.insert.sub!(/^#{Regexp.quote(sep)}/, '')
    end
    change.delete << sep if change.delete?
  else
    change = Change.new(:delete => @raw.empty? ? '' : sep)
  end
  @raw << change
  @raw.last.delete << str.join(sep)
end