Remove unused code

Author: Alexander Melentyev

metrics/cloudwatch/cloudwatch.go

@@ -271,10 +271,6 @@ func sum(a []float64) float64 {
 	return v
 }
 
-func last(a []float64) float64 {
-	return a[len(a)-1]
-}
-
 func min(a, b int) int {
 	if a < b {
 		return a

metrics/dogstatsd/dogstatsd.go

@@ -209,10 +209,6 @@ func sum(a []float64) float64 {
 	return v
 }
 
-func last(a []float64) float64 {
-	return a[len(a)-1]
-}
-
 func sampling(r float64) string {
 	var sv string
 	if r < 1.0 {

metrics/influxstatsd/influxstatsd.go

@@ -208,10 +208,6 @@ func sum(a []float64) float64 {
 	return v
 }
 
-func last(a []float64) float64 {
-	return a[len(a)-1]
-}
-
 func sampling(r float64) string {
 	var sv string
 	if r < 1.0 {

sd/zk/util_test.go

@@ -1,7 +1,6 @@
 package zk
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -17,7 +16,6 @@ import (
 
 var (
 	path   = "/gokit.test/service.name"
-	e      = func(context.Context, interface{}) (interface{}, error) { return struct{}{}, nil }
 	logger = log.NewNopLogger()
 )