diff --git a/examples/benchmark_grpc/client_local_test.go b/examples/benchmark_grpc/client_local_test.go
index 18ea87d..23003bf 100644
--- a/examples/benchmark_grpc/client_local_test.go
+++ b/examples/benchmark_grpc/client_local_test.go
@@ -15,7 +15,6 @@ func BenchmarkClientLocal(b *testing.B) {
 	// 2. getter: get a value from the worker
 	// 3. processing: call an operation based on the value
 	worker.Subscribe(func() {
-
 		// loop
 		i++
 		if i > limit {
diff --git a/examples/benchmark_grpc/server_arpc.go b/examples/benchmark_grpc/server_arpc.go
index 83e1124..60121ff 100644
--- a/examples/benchmark_grpc/server_arpc.go
+++ b/examples/benchmark_grpc/server_arpc.go
@@ -22,7 +22,6 @@ type WorkerArpcServer struct {
 func NewWorkerArpcServer(
 	ctx context.Context, addr string, worker *Worker,
 ) (*WorkerArpcServer, error) {
-
 	// validate
 	if worker == nil {
 		return nil, errors.New("worker is nil")
diff --git a/pkg/machine/machine.go b/pkg/machine/machine.go
index 040c7ed..db76bb7 100644
--- a/pkg/machine/machine.go
+++ b/pkg/machine/machine.go
@@ -1983,7 +1983,6 @@ func (m *Machine) processHandlers(e *Event) (Result, bool) {
 			// returns from State and End handlers are ignored
 		default:
 			if !ret {
-
 				return Canceled, handlerCalled
 			}
 		}
diff --git a/pkg/machine/misc.go b/pkg/machine/misc.go
index 3a55454..18c53f3 100644
--- a/pkg/machine/misc.go
+++ b/pkg/machine/misc.go
@@ -489,8 +489,6 @@ type (
 	IndexWhenArgs map[string][]*WhenArgsBinding
 	// IndexStateCtx is a map of (single) state names to a context cancel function
 	IndexStateCtx map[string][]context.CancelFunc
-	// map of (single) state names to an event channel
-	indexEventCh map[string][]chan *Event
 )
 
 type WhenBinding struct {
diff --git a/pkg/machine/misc_test.go b/pkg/machine/misc_test.go
index 0411662..16c3b7a 100644
--- a/pkg/machine/misc_test.go
+++ b/pkg/machine/misc_test.go
@@ -2,7 +2,6 @@ package machine
 
 import (
 	"context"
-	"os"
 	"testing"
 	"time"
 
@@ -129,11 +128,3 @@ func TestIsActiveTick(t *testing.T) {
 	assert.False(t, IsActiveTick(6548734))
 	assert.True(t, IsActiveTick(6548735))
 }
-
-func fileExists(filePath string) bool {
-	_, err := os.Stat(filePath)
-	if os.IsNotExist(err) {
-		return false
-	}
-	return err == nil
-}
diff --git a/pkg/machine/popup_test.go b/pkg/machine/popup_test.go
index 7cdf1df..71f87bb 100644
--- a/pkg/machine/popup_test.go
+++ b/pkg/machine/popup_test.go
@@ -5,8 +5,9 @@ import (
 	"testing"
 	"time"
 
-	am "github.com/pancsta/asyncmachine-go/pkg/machine"
 	"github.com/stretchr/testify/assert"
+
+	am "github.com/pancsta/asyncmachine-go/pkg/machine"
 )
 
 func NewPopupMachine(ctx context.Context) *am.Machine {
diff --git a/pkg/machine/transition.go b/pkg/machine/transition.go
index 7bd8632..8ae7424 100644
--- a/pkg/machine/transition.go
+++ b/pkg/machine/transition.go
@@ -394,7 +394,6 @@ func (t *Transition) emitEvents() Result {
 
 	// AUTO STATES
 	if result == Canceled {
-
 		t.Accepted = false
 	} else if hasStateChanged && !t.IsAuto() {
 
diff --git a/pkg/machine/utils_test.go b/pkg/machine/utils_test.go
index f261928..913739b 100644
--- a/pkg/machine/utils_test.go
+++ b/pkg/machine/utils_test.go
@@ -29,7 +29,6 @@ func (h *History) AC(e *Event) {
 
 func (h *History) AExit(e *Event) {
 	h.event("AExit")
-
 }
 
 func (h *History) AA(e *Event) {
@@ -64,7 +63,6 @@ func (h *History) AnyB(e *Event) {
 
 func (h *History) BExit(e *Event) {
 	h.event("BExit")
-
 }
 
 func (h *History) BD(e *Event) {
diff --git a/pkg/rpc/client.go b/pkg/rpc/client.go
index 96bc80f..92a6b5e 100644
--- a/pkg/rpc/client.go
+++ b/pkg/rpc/client.go
@@ -36,8 +36,10 @@ type Client struct {
 }
 
 // interfaces
-var _ clientRpcMethods = &Client{}
-var _ clientServerMethods = &Client{}
+var (
+	_ clientRpcMethods    = &Client{}
+	_ clientServerMethods = &Client{}
+)
 
 func NewClient(
 	ctx context.Context, workerAddr string, id string, stateStruct am.Struct,
@@ -182,7 +184,7 @@ func (c *Client) HandshakingState(e *am.Event) {
 
 	go func() {
 		// call rpc
-		var resp = &RespHandshake{}
+		resp := &RespHandshake{}
 		if !c.call(ctx, rpcnames.Handshake.Encode(), Empty{}, resp) {
 			return
 		}
diff --git a/pkg/rpc/rpc_machine_test.go b/pkg/rpc/rpc_machine_test.go
index aa04e6a..552dcf7 100644
--- a/pkg/rpc/rpc_machine_test.go
+++ b/pkg/rpc/rpc_machine_test.go
@@ -18,8 +18,10 @@ import (
 type S = am.S
 
 // type A = am.A
-type State = am.State
-type Struct = am.Struct
+type (
+	State  = am.State
+	Struct = am.Struct
+)
 
 func init() {
 	if os.Getenv("AM_TEST_DEBUG") != "" {
diff --git a/pkg/rpc/rpc_test.go b/pkg/rpc/rpc_test.go
index c3310d8..22b76ff 100644
--- a/pkg/rpc/rpc_test.go
+++ b/pkg/rpc/rpc_test.go
@@ -389,7 +389,6 @@ func NewTest(
 	t *testing.T, ctx context.Context, worker *am.Machine,
 	disposeMeter <-chan struct{}, clockInterval *time.Duration,
 ) (<-chan int64, *am.Machine, *Server, *Client) {
-
 	// read env
 	amDbgAddr := os.Getenv("AM_DBG_ADDR")
 	logLvl := am.EnvLogLevel("")
diff --git a/pkg/rpc/server.go b/pkg/rpc/server.go
index ab6f28d..a63ecbb 100644
--- a/pkg/rpc/server.go
+++ b/pkg/rpc/server.go
@@ -54,8 +54,10 @@ type Server struct {
 }
 
 // interfaces
-var _ serverRpcMethods = &Server{}
-var _ clientServerMethods = &Server{}
+var (
+	_ serverRpcMethods    = &Server{}
+	_ clientServerMethods = &Server{}
+)
 
 func NewServer(
 	ctx context.Context, addr string, id string, worker *am.Machine,
diff --git a/pkg/rpc/shared.go b/pkg/rpc/shared.go
index 6feae8f..429d345 100644
--- a/pkg/rpc/shared.go
+++ b/pkg/rpc/shared.go
@@ -126,10 +126,6 @@ var (
 
 // wrapping error setters
 
-func errResponse(mach *am.Machine, err error) {
-	mach.AddErr(fmt.Errorf("%w: %w", ErrInvalidResp, err), nil)
-}
-
 func errResponseStr(mach *am.Machine, msg string) {
 	mach.AddErr(fmt.Errorf("%w: %s", ErrInvalidResp, msg), nil)
 }
@@ -144,7 +140,6 @@ func errNetwork(mach *am.Machine, err error) {
 
 // errAuto detects sentinels from error msgs and wraps.
 func errAuto(mach *am.Machine, msg string, err error) {
-
 	// detect group from text
 	var errGroup error
 	if strings.HasPrefix(err.Error(), "gob: ") {
diff --git a/pkg/rpc/utils_test.go b/pkg/rpc/utils_test.go
index 1341c93..4118e02 100644
--- a/pkg/rpc/utils_test.go
+++ b/pkg/rpc/utils_test.go
@@ -5,9 +5,10 @@ import (
 	"testing"
 
 	"github.com/lithammer/dedent"
+	"github.com/stretchr/testify/assert"
+
 	am "github.com/pancsta/asyncmachine-go/pkg/machine"
 	"github.com/pancsta/asyncmachine-go/pkg/types"
-	"github.com/stretchr/testify/assert"
 )
 
 func assertStates(t *testing.T, m types.MachineApi, expected am.S,
diff --git a/pkg/rpc/worker.go b/pkg/rpc/worker.go
index 703b398..b869538 100644
--- a/pkg/rpc/worker.go
+++ b/pkg/rpc/worker.go
@@ -34,8 +34,8 @@ type Worker struct {
 	indexWhen        am.IndexWhen
 	indexWhenTime    am.IndexWhenTime
 	// TODO indexWhenArgs
-	indexWhenArgs am.IndexWhenArgs
-	whenDisposed  chan struct{}
+	// indexWhenArgs am.IndexWhenArgs
+	whenDisposed chan struct{}
 }
 
 // Worker implements MachineApi
@@ -1028,7 +1028,6 @@ func (w *Worker) processWhenTimeBindings(timeBefore am.Time) {
 	// collect all the ticked states
 	all := am.S{}
 	for idx, t := range timeBefore {
-
 		// if changed, collect to check
 		if w.clockTime[idx] != t {
 			all = append(all, w.stateNames[idx])
@@ -1037,7 +1036,6 @@ func (w *Worker) processWhenTimeBindings(timeBefore am.Time) {
 
 	// check all the bindings for all the ticked states
 	for _, s := range all {
-
 		for k, binding := range indexWhenTime[s] {
 
 			// check if the requested time has passed
@@ -1133,11 +1131,6 @@ func j(states []string) string {
 	return strings.Join(states, " ")
 }
 
-// jw joins state names into a single string with a separator.
-func jw(states []string, sep string) string {
-	return strings.Join(states, sep)
-}
-
 // disposeWithCtx handles early binding disposal caused by a canceled context.
 // It's used by most of "when" methods.
 func disposeWithCtx[T comparable](
@@ -1215,24 +1208,6 @@ func slicesEvery[S1 ~[]E, S2 ~[]E, E comparable](col1 S1, col2 S2) bool {
 	return true
 }
 
-func slicesFilter[S ~[]E, E any](coll S, fn func(item E, i int) bool) S {
-	var ret S
-	for i, el := range coll {
-		if fn(el, i) {
-			ret = append(ret, el)
-		}
-	}
-	return ret
-}
-
-func slicesReverse[S ~[]E, E any](coll S) S {
-	ret := make(S, len(coll))
-	for i := range coll {
-		ret[i] = coll[len(coll)-1-i]
-	}
-	return ret
-}
-
 func slicesUniq[S ~[]E, E comparable](coll S) S {
 	var ret S
 	for _, el := range coll {
diff --git a/pkg/states/ss_basic.go b/pkg/states/ss_basic.go
index bc8231a..da4e208 100644
--- a/pkg/states/ss_basic.go
+++ b/pkg/states/ss_basic.go
@@ -45,9 +45,7 @@ var States = am.Struct{
 
 // Groups of mutually exclusive states.
 
-var (
-	GroupConnected = S{Connecting, Connected, Disconnecting, Disconnected}
-)
+var GroupConnected = S{Connecting, Connected, Disconnecting, Disconnected}
 
 // #region boilerplate defs
 
diff --git a/pkg/telemetry/prometheus/prometheus.go b/pkg/telemetry/prometheus/prometheus.go
index 40e5ceb..1bd469e 100644
--- a/pkg/telemetry/prometheus/prometheus.go
+++ b/pkg/telemetry/prometheus/prometheus.go
@@ -1,4 +1,4 @@
-// Package prometheus provides Prometheus metrics for asyncamachine.
+// Package prometheus provides Prometheus metrics for asyncmachine.
 // Metrics are collected from machine's transitions and states.
 package prometheus
 
@@ -391,7 +391,8 @@ func TransitionsToPrometheus(
 	metrics.RelAmount.Set(float64(relCount))
 	metrics.RefStatesAmount.Set(float64(stateRefCount))
 
-	mach.Tracers = append(mach.Tracers, &promTracer{m: metrics})
+	metrics.tracer = &promTracer{m: metrics}
+	mach.Tracers = append(mach.Tracers, metrics.tracer)
 
 	return metrics
 }
diff --git a/pkg/telemetry/telemetry.go b/pkg/telemetry/telemetry.go
index 0b1b943..28bc4b1 100644
--- a/pkg/telemetry/telemetry.go
+++ b/pkg/telemetry/telemetry.go
@@ -86,11 +86,9 @@ type DbgMsgTx struct {
 func (d *DbgMsgTx) Clock(statesIndex am.S, state string) uint64 {
 	idx := lo.IndexOf(statesIndex, state)
 	return d.Clocks[idx]
-
 }
 
 func (d *DbgMsgTx) Is(statesIndex am.S, states am.S) bool {
-
 	for _, state := range states {
 		idx := lo.IndexOf(statesIndex, state) //nolint:typecheck
 		if idx == -1 {
diff --git a/pkg/types/types.go b/pkg/types/types.go
index 33a535b..84b8e55 100644
--- a/pkg/types/types.go
+++ b/pkg/types/types.go
@@ -9,7 +9,6 @@ import (
 // MachineApi is a subset of `pkg/machine#Machine` for alternative
 // implementations.
 type MachineApi interface {
-
 	// ///// REMOTE
 
 	// Mutations (remote)
diff --git a/tools/debugger/handlers.go b/tools/debugger/handlers.go
index 7e56073..ab3ae20 100644
--- a/tools/debugger/handlers.go
+++ b/tools/debugger/handlers.go
@@ -871,7 +871,6 @@ func (d *Debugger) ToggleFilterState(_ *am.Event) {
 }
 
 func (d *Debugger) SwitchingClientTxState(e *am.Event) {
-
 	clientID, _ := e.Args["Client.id"].(string)
 	cursorTx, _ := e.Args["Client.cursorTx"].(int)
 	ctx := d.Mach.NewStateCtx(ss.SwitchingClientTx)