code: func (s *Stack) equal(r *Stack) bool {
  	if len(s.Calls) != len(r.Calls) || s.Elided != r.Elided {
  		return false
  	}
  	for i := range s.Calls {
  		if !s.Calls[i].equal(&r.Calls[i]) {
  			return false
  		}
  	}
  	return true
  }
docs: // equal returns true on if both call stacks are exactly equal.