code: func (s *TxStats) Sub(other *TxStats) TxStats {
  	var diff TxStats
  	diff.PageCount = s.PageCount - other.PageCount
  	diff.PageAlloc = s.PageAlloc - other.PageAlloc
  	diff.CursorCount = s.CursorCount - other.CursorCount
  	diff.NodeCount = s.NodeCount - other.NodeCount
  	diff.NodeDeref = s.NodeDeref - other.NodeDeref
  	diff.Rebalance = s.Rebalance - other.Rebalance
  	diff.RebalanceTime = s.RebalanceTime - other.RebalanceTime
  	diff.Split = s.Split - other.Split
  	diff.Spill = s.Spill - other.Spill
  	diff.SpillTime = s.SpillTime - other.SpillTime
  	diff.Write = s.Write - other.Write
  	diff.WriteTime = s.WriteTime - other.WriteTime
  	return diff
  }
docs: // Sub calculates and returns the difference between two sets of transaction stats.
  // This is useful when obtaining stats at two different points and time and
  // you need the performance counters that occurred within that time span.