global

def diff_traversal(method, seq1, seq2, callbacks, &block)
  callbacks = callbacks_for(callbacks)
  case method
  when :diff
    traverse_sequences(seq1, seq2, callbacks)
  when :sdiff
    traverse_balanced(seq1, seq2, callbacks)
  end
  callbacks.finish if callbacks.respond_to? :finish
  if block
    callbacks.diffs.map do |hunk|
      if hunk.kind_of? Array
        hunk.map { |hunk_block| block[hunk_block] }
      else
        block[hunk]
      end
    end
  else
    callbacks.diffs
  end
end