diff --git a/07_errors/hsy3418/error.go b/07_errors/hsy3418/error.go
new file mode 100644
index 000000000..69db6b971
--- /dev/null
+++ b/07_errors/hsy3418/error.go
@@ -0,0 +1,40 @@
+package main
+
+import "fmt"
+
+type Error struct {
+	Message string
+	Code    ErrorCode
+}
+
+func (e *Error) Error() string {
+	return fmt.Sprintf("Error code:%d,Error:%s", e.Code, e.Message)
+
+}
+
+// Errorf creates a new Error with formatting
+func Errorf(code ErrorCode, format string, args ...interface{}) *Error {
+	return ErrorEf(code, format, args...)
+}
+
+// ErrorEf creates a new Error with causing error and formatting
+func ErrorEf(code ErrorCode, format string, args ...interface{}) *Error {
+	return &Error{
+		Message: fmt.Sprintf(format, args...),
+		Code:    code,
+	}
+}
+
+//ErrCode defines the kind of error
+type ErrorCode uint8
+
+//Error codes
+const (
+	// ErrInvalidInput for invalid user input
+	ErrInvalidInput ErrorCode = iota
+	// ErrDuplicate is used when attempting to create an already existing entry
+	ErrDuplicate
+	// ErrNotFound is used when trying to access a non-existing entry
+	ErrNotFound
+	// ErrNotFound is used when initialisation or setup fails
+)
diff --git a/07_errors/hsy3418/error_test.go b/07_errors/hsy3418/error_test.go
new file mode 100644
index 000000000..308718bed
--- /dev/null
+++ b/07_errors/hsy3418/error_test.go
@@ -0,0 +1,28 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestInvalidInputError(t *testing.T) {
+	err := Errorf(ErrInvalidInput, "invalid input")
+	assert.Equal(t, err.Code, ErrInvalidInput)
+	errMessage := err.Error()
+	assert.Equal(t, "Error code:0,Error:invalid input", errMessage)
+}
+
+func TestNotFoundError(t *testing.T) {
+	err := Errorf(ErrNotFound, "error not found")
+	assert.Equal(t, err.Code, ErrNotFound)
+	errMessage := err.Error()
+	assert.Equal(t, "Error code:2,Error:error not found", errMessage)
+}
+
+func TestDuplicateError(t *testing.T) {
+	err := Errorf(ErrDuplicate, "duplicate value")
+	assert.Equal(t, err.Code, ErrDuplicate)
+	errMessage := err.Error()
+	assert.Equal(t, "Error code:1,Error:duplicate value", errMessage)
+}
diff --git a/07_errors/hsy3418/main.go b/07_errors/hsy3418/main.go
new file mode 100644
index 000000000..820427f1f
--- /dev/null
+++ b/07_errors/hsy3418/main.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+var out io.Writer = os.Stdout
+
+func main() {
+	p1 := Puppy{ID: 101, Breed: "Poodle", Colour: "White", Value: 1280.5}
+	p2 := Puppy{ID: 102, Breed: "Poodle", Colour: "Grey", Value: 1340.5}
+
+	mapStore := NewMapStore()
+	syncStore := NewSyncStore()
+
+	_ = mapStore.CreatePuppy(p1)
+	_ = syncStore.CreatePuppy(p2)
+
+	puppy, _ := mapStore.ReadPuppy(101)
+	puppy2, _ := syncStore.ReadPuppy(102)
+	fmt.Fprintf(out, "Puppy ID %d is %v", puppy.ID, puppy.Value)
+	fmt.Fprintf(out, "Puppy ID %d is %v", puppy2.ID, puppy2.Value)
+
+}
diff --git a/07_errors/hsy3418/main_test.go b/07_errors/hsy3418/main_test.go
new file mode 100644
index 000000000..95aeb49ae
--- /dev/null
+++ b/07_errors/hsy3418/main_test.go
@@ -0,0 +1,18 @@
+package main
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMain(t *testing.T) {
+	assert := assert.New(t)
+	var buf bytes.Buffer
+	out = &buf
+	main()
+	expected := "Puppy ID 101 is 1280.5Puppy ID 102 is 1340.5"
+	actual := buf.String()
+	assert.Equal(expected, actual)
+}
diff --git a/07_errors/hsy3418/mapStore.go b/07_errors/hsy3418/mapStore.go
new file mode 100644
index 000000000..989751118
--- /dev/null
+++ b/07_errors/hsy3418/mapStore.go
@@ -0,0 +1,53 @@
+package main
+
+// MapStore is a implementation of storer for the storage of puppies
+type MapStore struct {
+	puppies map[int32]Puppy
+}
+
+func NewMapStore() *MapStore {
+	return &MapStore{
+		puppies: map[int32]Puppy{},
+	}
+}
+
+// CreatePuppy adds a nuw puppy to the puppies store
+func (m *MapStore) CreatePuppy(puppy Puppy) error {
+	if puppy.Value < 0 {
+		return ErrorEf(ErrInvalidInput, "The puppy value is invalidate")
+	}
+	if _, exists := m.puppies[puppy.ID]; !exists {
+		m.puppies[puppy.ID] = puppy
+		return nil
+	}
+	return ErrorEf(ErrDuplicate, "This puppy exists ")
+}
+
+// ReadPuppy retrieves the puppy for a given id from puppies store
+func (m *MapStore) ReadPuppy(id int32) (Puppy, error) {
+	if _, exists := m.puppies[id]; !exists {
+		return Puppy{}, ErrorEf(ErrNotFound, "This puppy does not exist")
+	}
+	return m.puppies[id], nil
+}
+
+//UpdatePuppy updates the puppy for the given id
+func (m *MapStore) UpdatePuppy(puppy Puppy) error {
+	if puppy.Value < 0 {
+		return ErrorEf(ErrInvalidInput, "The puppy value is invalidate")
+	}
+	if _, exists := m.puppies[puppy.ID]; !exists {
+		return ErrorEf(ErrNotFound, "This puppy does not exist")
+	}
+	m.puppies[puppy.ID] = puppy
+	return nil
+}
+
+//DeletePuppy delete the puppy for the given id from puppies store
+func (m *MapStore) DeletePuppy(id int32) error {
+	if _, exists := m.puppies[id]; exists {
+		delete(m.puppies, id)
+		return nil
+	}
+	return ErrorEf(ErrNotFound, "This puppy does not exist")
+}
diff --git a/07_errors/hsy3418/store_test.go b/07_errors/hsy3418/store_test.go
new file mode 100644
index 000000000..88b596ceb
--- /dev/null
+++ b/07_errors/hsy3418/store_test.go
@@ -0,0 +1,131 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/suite"
+)
+
+func (suite *storerTestSuite) SetupTest() {
+	suite.store = suite.makeStore()
+	suite.toBeCreatedPuppy = Puppy{ID: 101, Breed: "Poodle", Colour: "White", Value: 1000.5}
+	suite.existsPuppy = Puppy{ID: 102, Breed: "Poodle", Colour: "White", Value: 1280.5}
+	suite.toBeUpdatedPuppy = Puppy{ID: 102, Breed: "Poodle", Colour: "White", Value: 2000}
+	suite.invalidPuppy = Puppy{ID: 103, Breed: "Poodle", Colour: "White", Value: -1000}
+	suite.invaildError = ErrorEf(ErrInvalidInput, "The puppy value is invalidate")
+	suite.invalidIDError = ErrorEf(ErrNotFound, "This puppy does not exist")
+	suite.dupicatesError = ErrorEf(ErrDuplicate, "This puppy exists ")
+	err := suite.store.CreatePuppy(suite.existsPuppy)
+	if err != nil {
+		suite.FailNow("Failed to setup test")
+	}
+}
+
+type storerTestSuite struct {
+	suite.Suite
+	store            Storer
+	makeStore        func() Storer
+	toBeCreatedPuppy Puppy
+	existsPuppy      Puppy
+	toBeUpdatedPuppy Puppy
+	invalidPuppy     Puppy
+	invaildError     error
+	invalidIDError   error
+	dupicatesError   error
+}
+
+//successfully create puppy, new puppy, existing puppy, value <0
+func (suite *storerTestSuite) TestCreatePuppy() {
+	assert := assert.New(suite.T())
+	testCases := []struct {
+		title    string
+		input    Puppy
+		expected error
+	}{
+		{"Create new puppy", suite.toBeCreatedPuppy, nil},
+		{"Create existing puppy", suite.toBeCreatedPuppy, suite.dupicatesError},
+		{"Create a invalid puppy", suite.invalidPuppy, suite.invaildError},
+	}
+	for _, tc := range testCases {
+		tc := tc
+		suite.T().Run(tc.title, func(t *testing.T) {
+			err := suite.store.CreatePuppy(tc.input)
+			assert.Equal(tc.expected, err)
+		})
+	}
+
+}
+
+//
+func (suite *storerTestSuite) TestUpdatePuppy() {
+	assert := assert.New(suite.T())
+	testCases := []struct {
+		title         string
+		inputPuppy    Puppy
+		expectedError error
+	}{
+		{"Update puppy successfully", suite.toBeUpdatedPuppy, nil},
+		{"Update a invalid puppy", suite.invalidPuppy, suite.invaildError},
+		{"Update non-existing puppy", Puppy{}, suite.invalidIDError},
+	}
+	for _, tc := range testCases {
+		tc := tc
+		suite.T().Run(tc.title, func(t *testing.T) {
+			err := suite.store.UpdatePuppy(tc.inputPuppy)
+			assert.Equal(tc.expectedError, err)
+		})
+	}
+
+}
+
+func (suite *storerTestSuite) TestReadPuppy() {
+	assert := assert.New(suite.T())
+	testCases := []struct {
+		title         string
+		input         int32
+		expected      Puppy
+		expectedError error
+	}{
+		{"Read puppy successfully", suite.existsPuppy.ID, suite.existsPuppy, nil},
+		{"Read non-existing puppy", suite.toBeCreatedPuppy.ID, Puppy{}, suite.invalidIDError},
+	}
+	for _, tc := range testCases {
+		tc := tc
+		suite.T().Run(tc.title, func(t *testing.T) {
+			readPuppy, err := suite.store.ReadPuppy(tc.input)
+			assert.Equal(tc.expected, readPuppy)
+			assert.Equal(tc.expectedError, err)
+		})
+	}
+
+}
+
+func (suite *storerTestSuite) TestDeletePuppy() {
+	assert := assert.New(suite.T())
+	testCases := []struct {
+		title         string
+		input         int32
+		expectedError error
+	}{
+		{"Delete puppy successfully", suite.existsPuppy.ID, nil},
+		{"Delete non-existing puppy", suite.toBeCreatedPuppy.ID, suite.invalidIDError},
+	}
+	for _, tc := range testCases {
+		tc := tc
+		suite.T().Run(tc.title, func(t *testing.T) {
+			err := suite.store.DeletePuppy(tc.input)
+			assert.Equal(tc.expectedError, err)
+		})
+	}
+
+}
+
+func TestStorers(t *testing.T) {
+	suite.Run(t, &storerTestSuite{
+		makeStore: func() Storer { return NewMapStore() },
+	})
+	suite.Run(t, &storerTestSuite{
+		makeStore: func() Storer { return NewSyncStore() },
+	})
+}
diff --git a/07_errors/hsy3418/syncStore.go b/07_errors/hsy3418/syncStore.go
new file mode 100644
index 000000000..43b13e4fb
--- /dev/null
+++ b/07_errors/hsy3418/syncStore.go
@@ -0,0 +1,63 @@
+package main
+
+import (
+	"sync"
+)
+
+type SyncStore struct {
+	sync.Mutex
+	sync.Map
+}
+
+func NewSyncStore() *SyncStore {
+	return &SyncStore{}
+}
+
+// CreatePuppy adds a nuw puppy to the puppies store
+func (m *SyncStore) CreatePuppy(puppy Puppy) error {
+	m.Lock()
+	defer m.Unlock()
+	if puppy.Value < 0 {
+		return ErrorEf(ErrInvalidInput, "The puppy value is invalidate")
+	}
+	if _, exists := m.Load(puppy.ID); exists {
+		return ErrorEf(ErrDuplicate, "This puppy exists ")
+	}
+	m.Store(puppy.ID, puppy)
+	return nil
+}
+
+// ReadPuppy retrieves the puppy for a given id from puppies store
+func (m *SyncStore) ReadPuppy(id int32) (Puppy, error) {
+	if p, exists := m.Load(id); exists {
+		puppy, _ := p.(Puppy)
+		return puppy, nil
+	}
+	return Puppy{}, ErrorEf(ErrNotFound, "This puppy does not exist")
+
+}
+
+//UpdatePuppy updates the puppy for the given id
+func (m *SyncStore) UpdatePuppy(puppy Puppy) error {
+	m.Lock()
+	defer m.Unlock()
+	if puppy.Value < 0 {
+		return ErrorEf(ErrInvalidInput, "The puppy value is invalidate")
+	}
+	if _, exists := m.Load(puppy.ID); !exists {
+		return ErrorEf(ErrNotFound, "This puppy does not exist")
+	}
+	m.Store(puppy.ID, puppy)
+	return nil
+}
+
+//DeletePuppy delete the puppy for the given id from puppies store
+func (m *SyncStore) DeletePuppy(id int32) error {
+	m.Lock()
+	defer m.Unlock()
+	if _, exists := m.Load(id); exists {
+		m.Delete(id)
+		return nil
+	}
+	return ErrorEf(ErrNotFound, "This puppy does not exist")
+}
diff --git a/07_errors/hsy3418/types.go b/07_errors/hsy3418/types.go
new file mode 100644
index 000000000..fa6bf05d9
--- /dev/null
+++ b/07_errors/hsy3418/types.go
@@ -0,0 +1,17 @@
+package main
+
+// Puppy defines the data structure corresponding to a pet
+type Puppy struct {
+	ID     int32   `json:"id"`
+	Value  float32 `json:"value"`
+	Breed  string  `json:"breed"`
+	Colour string  `json:"colour"`
+}
+
+//Storer define standard CRUD operations for puppys
+type Storer interface {
+	CreatePuppy(Puppy) error
+	ReadPuppy(ID int32) (Puppy, error)
+	UpdatePuppy(puppy Puppy) error
+	DeletePuppy(ID int32) error
+}