code: func equivalent(path string, a, b *object.Commit) (bool, error) {
  	numParentsA := a.NumParents()
  	numParentsB := b.NumParents()
  
  	// the first commit is not equivalent to anyone
  	// and "I think" merges can not be equivalent to anything
  	if numParentsA != 1 || numParentsB != 1 {
  		return false, nil
  	}
  
  	diffsA, err := patch(a, path)
  	if err != nil {
  		return false, err
  	}
  	diffsB, err := patch(b, path)
  	if err != nil {
  		return false, err
  	}
  
  	return sameDiffs(diffsA, diffsB), nil
  }
docs: // Equivalent commits are commits whose patch is the same.