Remove unused id field

log_counter.go

diff --git a/log_counter.go b/log_counter.go
index cada5cc..570db1d 100644
--- a/log_counter.go
+++ b/log_counter.go
@@ -10,7 +10,6 @@
 )
 
 type logCounter struct {
-	id      int
 	counter uint64
 }
 

notepad.go

diff --git a/notepad.go b/notepad.go
index 40b9620..ea34586 100644
--- a/notepad.go
+++ b/notepad.go
@@ -101,7 +101,7 @@
 
 	for t, logger := range n.loggers {
 		threshold := Threshold(t)
-		counter := &logCounter{id: t}
+		counter := &logCounter{}
 		n.logCounters[t] = counter
 
 		switch {