code: func (q *Query) WriteCallN() int {
  	var n int
  	for _, call := range q.Calls {
  		switch call.Name {
  		case "Set", "Clear", "SetRowAttrs", "SetColumnAttrs":
  			n++
  		}
  	}
  	return n
  }
docs: // WriteCallN returns the number of mutating calls.