class Diff::LCS::Hunk

def diff(format, last = false)
  case format
  when :old
    old_diff(last)
  when :unified
    unified_diff(last)
  when :context
    context_diff(last)
  when :ed
    self
  when :reverse_ed, :ed_finish
    ed_diff(format, last)
  else
    fail "Unknown diff format #{format}."
  end
end