def diff(*args)
      args.unshift(parents.first) if args.size == 1 && args.first.is_a?(Hash)
      self.tree.diff(*args)
    end
def diff(*args)
      args.unshift(parents.first) if args.size == 1 && args.first.is_a?(Hash)
      self.tree.diff(*args)
    end
Return a diff between this commit and its first parent or another commit or tree.

 See Rugged::Tree#diff for more details.