diff --git a/Makefile b/Makefile
index ec0e94b..f05e1b4 100644
--- a/Makefile
+++ b/Makefile
@@ -44,7 +44,7 @@ test_ci: ## Run tests using normal test runner for ci output.
 
 test_data:  ## Creates test data from the ONNX test module.
 	rm -R ./test_data; mkdir ./test_data; touch ./test_data/
-	git clone --depth 1 --branch v1.15.0 https://github.com/onnx/onnx.git temp_onnx
+	git clone --depth 1 --branch v1.17.0 https://github.com/onnx/onnx.git temp_onnx
 	cp -r temp_onnx/onnx/backend/test/data/node/* ./test_data
 	rm -Rf temp_onnx
 
diff --git a/ops/constant/constant_1.go b/ops/constant/constant_1.go
index 9fd18c0..964f6b6 100644
--- a/ops/constant/constant_1.go
+++ b/ops/constant/constant_1.go
@@ -26,7 +26,7 @@ func (c *Constant1) Init(n *onnx.NodeProto) error {
 	attr := attributes[0]
 
 	switch attr.GetName() {
-	case "value":
+	case value:
 		t, err := onnx.TensorFromProto(attr.GetT())
 		if err != nil {
 			return err
diff --git a/ops/constant/constant_11.go b/ops/constant/constant_11.go
index b10b7ea..b5de777 100644
--- a/ops/constant/constant_11.go
+++ b/ops/constant/constant_11.go
@@ -27,9 +27,9 @@ func (c *Constant11) Init(n *onnx.NodeProto) error {
 	attr := attributes[0]
 
 	switch attr.GetName() {
-	case "sparse_value":
+	case sparseValue:
 		return ops.ErrUnsupportedAttribute(attr.GetName(), c)
-	case "value":
+	case value:
 		t, err := onnx.TensorFromProto(attr.GetT())
 		if err != nil {
 			return err
diff --git a/ops/constant/constant_12.go b/ops/constant/constant_12.go
index 0174bea..3390b49 100644
--- a/ops/constant/constant_12.go
+++ b/ops/constant/constant_12.go
@@ -27,23 +27,23 @@ func (c *Constant12) Init(n *onnx.NodeProto) error {
 	attr := attributes[0]
 
 	switch attr.GetName() {
-	case "sparse_value", "value_string", "value_strings":
+	case sparseValue, valueString, valueStrings:
 		return ops.ErrUnsupportedAttribute(attr.GetName(), c)
-	case "value":
+	case value:
 		t, err := onnx.TensorFromProto(attr.GetT())
 		if err != nil {
 			return err
 		}
 
 		c.value = t
-	case "value_float":
+	case valueFloat:
 		c.value = tensor.New(tensor.FromScalar(attr.GetF()))
-	case "value_floats":
+	case valueFloats:
 		floats := attr.GetFloats()
 		c.value = tensor.New(tensor.WithShape(len(floats)), tensor.WithBacking(floats))
-	case "value_int":
+	case valueInt:
 		c.value = tensor.New(tensor.FromScalar(attr.GetI()))
-	case "value_ints":
+	case valueInts:
 		ints := attr.GetInts()
 		c.value = tensor.New(tensor.WithShape(len(ints)), tensor.WithBacking(ints))
 	default:
diff --git a/ops/constant/constant_13.go b/ops/constant/constant_13.go
index 85261bc..c75f629 100644
--- a/ops/constant/constant_13.go
+++ b/ops/constant/constant_13.go
@@ -27,23 +27,23 @@ func (c *Constant13) Init(n *onnx.NodeProto) error {
 	attr := attributes[0]
 
 	switch attr.GetName() {
-	case "sparse_value", "value_string", "value_strings":
+	case sparseValue, valueString, valueStrings:
 		return ops.ErrUnsupportedAttribute(attr.GetName(), c)
-	case "value":
+	case value:
 		t, err := onnx.TensorFromProto(attr.GetT())
 		if err != nil {
 			return err
 		}
 
 		c.value = t
-	case "value_float":
+	case valueFloat:
 		c.value = tensor.New(tensor.FromScalar(attr.GetF()))
-	case "value_floats":
+	case valueFloats:
 		floats := attr.GetFloats()
 		c.value = tensor.New(tensor.WithShape(len(floats)), tensor.WithBacking(floats))
-	case "value_int":
+	case valueInt:
 		c.value = tensor.New(tensor.FromScalar(attr.GetI()))
-	case "value_ints":
+	case valueInts:
 		ints := attr.GetInts()
 		c.value = tensor.New(tensor.WithShape(len(ints)), tensor.WithBacking(ints))
 	default:
diff --git a/ops/constant/constant_9.go b/ops/constant/constant_9.go
index 08b6830..fe054dd 100644
--- a/ops/constant/constant_9.go
+++ b/ops/constant/constant_9.go
@@ -26,7 +26,7 @@ func (c *Constant9) Init(n *onnx.NodeProto) error {
 	attr := attributes[0]
 
 	switch attr.GetName() {
-	case "value":
+	case value:
 		t, err := onnx.TensorFromProto(attr.GetT())
 		if err != nil {
 			return err
diff --git a/ops/flatten/flatten_1.go b/ops/flatten/flatten_1.go
index 42f20fa..c2c6b66 100644
--- a/ops/flatten/flatten_1.go
+++ b/ops/flatten/flatten_1.go
@@ -27,7 +27,7 @@ func newFlatten1() ops.Operator {
 func (f *Flatten1) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "axis":
+		case axis:
 			f.axis = int(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), f)
@@ -40,6 +40,7 @@ func (f *Flatten1) Init(n *onnx.NodeProto) error {
 // Apply applies the flatten operator.
 func (f *Flatten1) Apply(inputs []tensor.Tensor) ([]tensor.Tensor, error) {
 	inputShape := inputs[0].Shape()
+
 	out, ok := inputs[0].Clone().(tensor.Tensor)
 	if !ok {
 		return nil, ops.ErrTypeAssert("tensor.Tensor", inputs[0].Clone())
diff --git a/ops/flatten/flatten_11.go b/ops/flatten/flatten_11.go
index 55685e4..d483365 100644
--- a/ops/flatten/flatten_11.go
+++ b/ops/flatten/flatten_11.go
@@ -27,7 +27,7 @@ func newFlatten11() ops.Operator {
 func (f *Flatten11) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "axis":
+		case axis:
 			f.axis = int(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), f)
diff --git a/ops/flatten/flatten_13.go b/ops/flatten/flatten_13.go
index 621f74c..190831d 100644
--- a/ops/flatten/flatten_13.go
+++ b/ops/flatten/flatten_13.go
@@ -27,7 +27,7 @@ func newFlatten13() ops.Operator {
 func (f *Flatten13) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "axis":
+		case axis:
 			f.axis = int(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), f)
diff --git a/ops/flatten/flatten_9.go b/ops/flatten/flatten_9.go
index b7f5c45..1932954 100644
--- a/ops/flatten/flatten_9.go
+++ b/ops/flatten/flatten_9.go
@@ -27,7 +27,7 @@ func newFlatten9() ops.Operator {
 func (f *Flatten9) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "axis":
+		case axis:
 			f.axis = int(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), f)
@@ -40,6 +40,7 @@ func (f *Flatten9) Init(n *onnx.NodeProto) error {
 // Apply applies the flatten operator.
 func (f *Flatten9) Apply(inputs []tensor.Tensor) ([]tensor.Tensor, error) {
 	inputShape := inputs[0].Shape()
+
 	out, ok := inputs[0].Clone().(tensor.Tensor)
 	if !ok {
 		return nil, ops.ErrTypeAssert("tensor.Tensor", inputs[0].Clone())
diff --git a/ops/gather/gather_1.go b/ops/gather/gather_1.go
index 01cdce4..0198f7d 100644
--- a/ops/gather/gather_1.go
+++ b/ops/gather/gather_1.go
@@ -30,7 +30,7 @@ func (g *Gather1) Init(n *onnx.NodeProto) error {
 	if len(attributes) == 1 {
 		attr := attributes[0]
 
-		if attr.GetName() == "axis" {
+		if attr.GetName() == axis {
 			g.axis = int(attr.GetI())
 		} else {
 			return ops.ErrInvalidAttribute(attr.GetName(), g)
diff --git a/ops/gather/gather_11.go b/ops/gather/gather_11.go
index 3677d39..a3f8358 100644
--- a/ops/gather/gather_11.go
+++ b/ops/gather/gather_11.go
@@ -30,7 +30,7 @@ func (g *Gather11) Init(n *onnx.NodeProto) error {
 	if len(attributes) == 1 {
 		attr := attributes[0]
 
-		if attr.GetName() == "axis" {
+		if attr.GetName() == axis {
 			g.axis = int(attr.GetI())
 		} else {
 			return ops.ErrInvalidAttribute(attr.GetName(), g)
diff --git a/ops/gather/gather_13.go b/ops/gather/gather_13.go
index f4bd7fc..2c72ea0 100644
--- a/ops/gather/gather_13.go
+++ b/ops/gather/gather_13.go
@@ -30,7 +30,7 @@ func (g *Gather13) Init(n *onnx.NodeProto) error {
 	if len(attributes) == 1 {
 		attr := attributes[0]
 
-		if attr.GetName() == "axis" {
+		if attr.GetName() == axis {
 			g.axis = int(attr.GetI())
 		} else {
 			return ops.ErrInvalidAttribute(attr.GetName(), g)
diff --git a/ops/gemm/gemm_11.go b/ops/gemm/gemm_11.go
index 44c7638..ae9d71f 100644
--- a/ops/gemm/gemm_11.go
+++ b/ops/gemm/gemm_11.go
@@ -33,13 +33,13 @@ func newGemm11() ops.Operator {
 func (g *Gemm11) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "alpha":
+		case alpha:
 			g.alpha = attr.GetF()
-		case "beta":
+		case beta:
 			g.beta = attr.GetF()
-		case "transA":
+		case transA:
 			g.transA = ops.Int64ToBool(attr.GetI())
-		case "transB":
+		case transB:
 			g.transB = ops.Int64ToBool(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), g)
diff --git a/ops/gemm/gemm_13.go b/ops/gemm/gemm_13.go
index b3c6de9..b67516b 100644
--- a/ops/gemm/gemm_13.go
+++ b/ops/gemm/gemm_13.go
@@ -33,13 +33,13 @@ func newGemm13() ops.Operator {
 func (g *Gemm13) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "alpha":
+		case alpha:
 			g.alpha = attr.GetF()
-		case "beta":
+		case beta:
 			g.beta = attr.GetF()
-		case "transA":
+		case transA:
 			g.transA = ops.Int64ToBool(attr.GetI())
-		case "transB":
+		case transB:
 			g.transB = ops.Int64ToBool(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), g)
diff --git a/ops/gemm/gemm_7.go b/ops/gemm/gemm_7.go
index b7192f8..19a7cd2 100644
--- a/ops/gemm/gemm_7.go
+++ b/ops/gemm/gemm_7.go
@@ -33,13 +33,13 @@ func newGemm7() ops.Operator {
 func (g *Gemm7) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "alpha":
+		case alpha:
 			g.alpha = attr.GetF()
-		case "beta":
+		case beta:
 			g.beta = attr.GetF()
-		case "transA":
+		case transA:
 			g.transA = ops.Int64ToBool(attr.GetI())
-		case "transB":
+		case transB:
 			g.transB = ops.Int64ToBool(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), g)
diff --git a/ops/gemm/gemm_9.go b/ops/gemm/gemm_9.go
index b06fb1c..f7d38db 100644
--- a/ops/gemm/gemm_9.go
+++ b/ops/gemm/gemm_9.go
@@ -33,13 +33,13 @@ func newGemm9() ops.Operator {
 func (g *Gemm9) Init(n *onnx.NodeProto) error {
 	for _, attr := range n.GetAttribute() {
 		switch attr.GetName() {
-		case "alpha":
+		case alpha:
 			g.alpha = attr.GetF()
-		case "beta":
+		case beta:
 			g.beta = attr.GetF()
-		case "transA":
+		case transA:
 			g.transA = ops.Int64ToBool(attr.GetI())
-		case "transB":
+		case transB:
 			g.transB = ops.Int64ToBool(attr.GetI())
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), g)
diff --git a/ops/matmul/matmul_1.go b/ops/matmul/matmul_1.go
index d106b3b..420b99c 100644
--- a/ops/matmul/matmul_1.go
+++ b/ops/matmul/matmul_1.go
@@ -134,7 +134,7 @@ func (m *MatMul1) GetInputTypeConstraints() [][]tensor.Dtype {
 
 // String implements the stringer interface, and can be used to format errors or messages.
 func (m *MatMul1) String() string {
-	return "matmul13 operator"
+	return "matmul1 operator"
 }
 
 // broadcastTensors broadcasts both tensors for the matmul operator. It is almost identical
diff --git a/ops/matmul/matmul_9.go b/ops/matmul/matmul_9.go
index 7beac84..3673553 100644
--- a/ops/matmul/matmul_9.go
+++ b/ops/matmul/matmul_9.go
@@ -134,7 +134,7 @@ func (m *MatMul9) GetInputTypeConstraints() [][]tensor.Dtype {
 
 // String implements the stringer interface, and can be used to format errors or messages.
 func (m *MatMul9) String() string {
-	return "matmul13 operator"
+	return "matmul9 operator"
 }
 
 // broadcastTensors broadcasts both tensors for the matmul operator. It is almost identical
diff --git a/ops/reducemax/reduce_max_1.go b/ops/reducemax/reduce_max_1.go
index 8b5f901..2cd8863 100644
--- a/ops/reducemax/reduce_max_1.go
+++ b/ops/reducemax/reduce_max_1.go
@@ -34,14 +34,14 @@ func (r *ReduceMax1) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/reducemax/reduce_max_11.go b/ops/reducemax/reduce_max_11.go
index b40be9a..24c5300 100644
--- a/ops/reducemax/reduce_max_11.go
+++ b/ops/reducemax/reduce_max_11.go
@@ -34,14 +34,14 @@ func (r *ReduceMax11) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/reducemax/reduce_max_12.go b/ops/reducemax/reduce_max_12.go
index 8139cfa..1bbcd6a 100644
--- a/ops/reducemax/reduce_max_12.go
+++ b/ops/reducemax/reduce_max_12.go
@@ -34,14 +34,14 @@ func (r *ReduceMax12) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/reducemax/reduce_max_13.go b/ops/reducemax/reduce_max_13.go
index f474ba2..f0801fd 100644
--- a/ops/reducemax/reduce_max_13.go
+++ b/ops/reducemax/reduce_max_13.go
@@ -34,14 +34,14 @@ func (r *ReduceMax13) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/reducemin/reduce_min_1.go b/ops/reducemin/reduce_min_1.go
index 5704ae0..91cdb3f 100644
--- a/ops/reducemin/reduce_min_1.go
+++ b/ops/reducemin/reduce_min_1.go
@@ -34,14 +34,14 @@ func (r *ReduceMin1) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/reducemin/reduce_min_11.go b/ops/reducemin/reduce_min_11.go
index 8c58d5c..4ebddb2 100644
--- a/ops/reducemin/reduce_min_11.go
+++ b/ops/reducemin/reduce_min_11.go
@@ -34,14 +34,14 @@ func (r *ReduceMin11) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/reducemin/reduce_min_12.go b/ops/reducemin/reduce_min_12.go
index 93a6f21..dfb41db 100644
--- a/ops/reducemin/reduce_min_12.go
+++ b/ops/reducemin/reduce_min_12.go
@@ -34,14 +34,14 @@ func (r *ReduceMin12) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/reducemin/reduce_min_13.go b/ops/reducemin/reduce_min_13.go
index 6ab63cd..be24e55 100644
--- a/ops/reducemin/reduce_min_13.go
+++ b/ops/reducemin/reduce_min_13.go
@@ -34,14 +34,14 @@ func (r *ReduceMin13) Init(n *onnx.NodeProto) error {
 
 	for _, attr := range attributes {
 		switch attr.GetName() {
-		case "axes":
+		case axes:
 			axes, err := ops.AnyToIntSlice(attr.GetInts())
 			if err != nil {
 				return err
 			}
 
 			r.axes = axes
-		case "keepdims":
+		case keepDims:
 			r.keepDims = attr.GetI() == 1
 		default:
 			return ops.ErrInvalidAttribute(attr.GetName(), r)
diff --git a/ops/slice/slice_1.go b/ops/slice/slice_1.go
index 13720c6..45e8df2 100644
--- a/ops/slice/slice_1.go
+++ b/ops/slice/slice_1.go
@@ -7,8 +7,10 @@ import (
 )
 
 const (
-	MinSlice1Inputs = 3
-	MaxSlice1Inputs = 5
+	MinSliceAttributes = 2
+	MaxSliceAttributes = 3
+	MinSlice1Inputs    = 3
+	MaxSlice1Inputs    = 5
 )
 
 // Slice1 represents the ONNX slice operator.
@@ -27,7 +29,7 @@ func newSlice1() ops.Operator {
 func (s *Slice1) Init(n *onnx.NodeProto) error {
 	nAttrs := len(n.GetAttribute())
 	if nAttrs < 2 || nAttrs > 3 {
-		return ops.ErrInvalidOptionalAttributeCount(2, 3, nAttrs, s)
+		return ops.ErrInvalidOptionalAttributeCount(MinSliceAttributes, MaxSliceAttributes, nAttrs, s)
 	}
 
 	for _, attr := range n.GetAttribute() {
@@ -109,7 +111,7 @@ func (s *Slice1) GetInputTypeConstraints() [][]tensor.Dtype {
 
 // String implements the stringer interface, and can be used to format errors or messages.
 func (s *Slice1) String() string {
-	return "slice11 operator"
+	return "slice1 operator"
 }
 
 // constructSlice constructs a list with tensor.Slice objects. The list is initializes with nils.
diff --git a/ops/slice/slice_10.go b/ops/slice/slice_10.go
index 30d41cf..48687cf 100644
--- a/ops/slice/slice_10.go
+++ b/ops/slice/slice_10.go
@@ -93,7 +93,7 @@ func (s *Slice10) GetInputTypeConstraints() [][]tensor.Dtype {
 
 // String implements the stringer interface, and can be used to format errors or messages.
 func (s *Slice10) String() string {
-	return "slice11 operator"
+	return "slice10 operator"
 }
 
 // constructSlice constructs a list with tensor.Slice objects. The list is initializes with nils.
diff --git a/ops/squeeze/squeeze_1.go b/ops/squeeze/squeeze_1.go
index 548594e..13faf2b 100644
--- a/ops/squeeze/squeeze_1.go
+++ b/ops/squeeze/squeeze_1.go
@@ -57,10 +57,7 @@ func (s *Squeeze1) Apply(inputs []tensor.Tensor) ([]tensor.Tensor, error) {
 	ops.OffsetArrayIfNegative(dimsToSqueeze, nDims)
 
 	if len(s.axes) > 0 {
-		dimsToSqueeze, err = getDimsToSqueezeFromList(s.axes, nDims)
-		if err != nil {
-			return nil, err
-		}
+		dimsToSqueeze = getDimsToSqueezeFromList(s.axes, nDims)
 	}
 
 	newShape := getNewShape(currentShape, dimsToSqueeze)
diff --git a/ops/squeeze/squeeze_11.go b/ops/squeeze/squeeze_11.go
index 35ffc81..cda72bb 100644
--- a/ops/squeeze/squeeze_11.go
+++ b/ops/squeeze/squeeze_11.go
@@ -57,10 +57,7 @@ func (s *Squeeze11) Apply(inputs []tensor.Tensor) ([]tensor.Tensor, error) {
 	ops.OffsetArrayIfNegative(dimsToSqueeze, nDims)
 
 	if len(s.axes) > 0 {
-		dimsToSqueeze, err = getDimsToSqueezeFromList(s.axes, nDims)
-		if err != nil {
-			return nil, err
-		}
+		dimsToSqueeze = getDimsToSqueezeFromList(s.axes, nDims)
 	}
 
 	newShape := getNewShape(currentShape, dimsToSqueeze)
@@ -105,7 +102,7 @@ func (s *Squeeze11) String() string {
 // based on a list of ints. The list should contain dimensions/axes to squeeze. Negative dimensions
 // represent dimensions counting from the end of the shape, i.e. -2 repesents the second
 // last dimension.
-func getDimsToSqueezeFromList(axes []int, nDims int) ([]int, error) {
+func getDimsToSqueezeFromList(axes []int, nDims int) []int {
 	dimsToSqueeze := make([]int, len(axes))
 	copy(dimsToSqueeze, axes)
 
@@ -115,5 +112,5 @@ func getDimsToSqueezeFromList(axes []int, nDims int) ([]int, error) {
 		}
 	}
 
-	return dimsToSqueeze, nil
+	return dimsToSqueeze
 }
diff --git a/ops/transpose/transpose_13.go b/ops/transpose/transpose_13.go
index 1f76c7d..bda0183 100644
--- a/ops/transpose/transpose_13.go
+++ b/ops/transpose/transpose_13.go
@@ -25,19 +25,17 @@ func newTranspose13() ops.Operator {
 func (t *Transpose13) Init(n *onnx.NodeProto) error {
 	attributes := n.GetAttribute()
 
-	if len(attributes) != 1 {
-		return ops.ErrInvalidAttributeCount(1, len(attributes), t)
-	}
-
-	attr := attributes[0]
+	if len(attributes) == 1 {
+		attr := attributes[0]
 
-	if attr.GetName() != "perm" {
-		return ops.ErrInvalidAttribute(attr.GetName(), t)
-	}
+		if attr.GetName() != "perm" {
+			return ops.ErrInvalidAttribute(attr.GetName(), t)
+		}
 
-	attrPerm := attr.GetInts()
-	for _, val := range attrPerm {
-		t.perm = append(t.perm, int(val))
+		attrPerm := attr.GetInts()
+		for _, val := range attrPerm {
+			t.perm = append(t.perm, int(val))
+		}
 	}
 
 	return nil
diff --git a/ops/transpose/transpose_13_test.go b/ops/transpose/transpose_13_test.go
index c61398e..7163178 100644
--- a/ops/transpose/transpose_13_test.go
+++ b/ops/transpose/transpose_13_test.go
@@ -25,14 +25,6 @@ func TestTranspose13InitFailWrongAttribute(t *testing.T) {
 	assert.Equal(t, expected, err)
 }
 
-func TestTranspose13InitFailAttrCount(t *testing.T) {
-	trans := &Transpose13{}
-	err := trans.Init(ops.EmptyNodeProto())
-
-	expected := ops.ErrInvalidAttributeCount(1, 0, trans)
-	assert.Equal(t, expected, err)
-}
-
 func TestTranspose13(t *testing.T) {
 	tests := []struct {
 		trans           *Transpose13
diff --git a/ops_test.go b/ops_test.go
index 7d017f5..4ea05dd 100644
--- a/ops_test.go
+++ b/ops_test.go
@@ -35,6 +35,7 @@ var ignoredTests = []string{
 	"test_logsoftmax_axis_2_expanded_ver18",          // Opset18
 	"test_lstm_batchwise",                            // Opset14
 	"test_mul_uint8",                                 // Opset14
+	"test_reduce_max_empty_set",                      // Opset20
 	"test_reduce_max_do_not_keepdims_random",         // Opset18
 	"test_reduce_max_keepdims_random",                // Opset18
 	"test_reduce_max_default_axes_keepdims_random",   // Opset18
@@ -75,9 +76,6 @@ var ignoredTests = []string{
 
 	"test_constant_pad",                      // Pad is not implemented yet.
 	"test_constant_pad_axes",                 // Pad is not implemented yet.
-	"test_gemm_alpha",                        // For gemm in opset 11.
-	"test_gemm_default_no_bias",              // For gemm in opset 11.
-	"test_gemm_default_scalar_bias",          // For gemm in opset 11.
 	"test_logsoftmax_large_number_expanded",  // Requires 'Exp' operator.
 	"test_logsoftmax_axis_0_expanded",        // Requires 'Exp' operator.
 	"test_logsoftmax_axis_1_expanded",        // Requires 'Exp' operator.
@@ -98,7 +96,6 @@ var ignoredTests = []string{
 	"test_slice_end_out_of_bounds",           // ONNX expects nil output, but we throw an error.
 	"test_slice_neg_steps",                   // ONNX expects nil output, but we throw an error.
 	"test_slice_neg",                         // ONNX expects nil output, but we throw an error.
-	"test_transpose_default",                 // For transpose in opset 9.
 
 	"test_equal_string",                               // Unsupported datatype String.
 	"test_equal_string_broadcast",                     // Unsupported datatype String.
@@ -145,7 +142,6 @@ var ignoredTests = []string{
 	"test_cast_no_saturate_FLOAT16_to_FLOAT8E4M3FN",   // Unsupported datatype.
 	"test_cast_no_saturate_FLOAT16_to_FLOAT8E5M2",     // Unsupported datatype.
 
-	"test_unsqueeze_axis_3",                 // Tests an old version of Unsqueeze (<= 11)
 	"test_constantofshape_int_shape_zero",   // Empty tensors are not supported in gorgonia
 	"test_gather_elements_0",                // Operator GatherElements is not implemented
 	"test_gather_elements_1",                // Operator GatherElements is not implemented
@@ -303,9 +299,14 @@ func readTestModel(folder string) (*Model, error) {
 		return nil, err
 	}
 
-	// Currently we only implemented Opset13, hence we enforce this in our tests. All
+	// Currently we support Opset 7-13, hence we enforce this in our tests. All
 	// tests that fail because of this are ignored.
-	mp.OpsetImport[0].Version = 13
+	fmt.Println(folder, mp.OpsetImport[0].Version)
+	if mp.OpsetImport[0].Version < MinSupportedOpset {
+		mp.OpsetImport[0].Version = MinSupportedOpset
+	} else if mp.OpsetImport[0].Version > MaxSupportedOpset {
+		mp.OpsetImport[0].Version = MaxSupportedOpset
+	}
 
 	model, err := NewModel(mp)
 	if err != nil {
@@ -424,7 +425,10 @@ var expectedTests = []string{
 	"test_gather_negative_indices",
 	"test_gemm_default_single_elem_vector_bias",
 	"test_gemm_all_attributes",
+	"test_gemm_alpha",
 	"test_gemm_default_matrix_bias",
+	"test_gemm_default_no_bias",
+	"test_gemm_default_scalar_bias",
 	"test_gemm_default_vector_bias",
 	"test_gemm_transposeA",
 	"test_gemm_default_zero_bias",
@@ -514,6 +518,7 @@ var expectedTests = []string{
 	"test_transpose_all_permutations_3",
 	"test_transpose_all_permutations_4",
 	"test_transpose_all_permutations_5",
+	"test_transpose_default",
 	"test_unsqueeze_axis_0",
 	"test_unsqueeze_axis_1",
 	"test_unsqueeze_axis_2",
diff --git a/opset.go b/opset.go
index 156117e..b307965 100644
--- a/opset.go
+++ b/opset.go
@@ -133,7 +133,7 @@ var operators = map[string]ops.OperatorVersions{
 // one is used. If the opset version is 13, and an operator has versions 7 and 14, version 7 is used, as
 // it is the closest opset version going downwards.
 func GetClosestOperatorVersion(opsetID int64, versions ops.OperatorVersions) func() ops.Operator {
-	for closestOpset := opsetID; opsetID >= MinSupportedOpset; closestOpset-- {
+	for closestOpset := opsetID; closestOpset >= 1; closestOpset-- {
 		if operator, ok := versions[closestOpset]; ok {
 			return operator
 		}
@@ -149,6 +149,7 @@ func ResolveOpset(opsetID int64) (Opset, error) {
 	}
 
 	opset := map[string]func() ops.Operator{}
+
 	for operatorName, operatorVersions := range operators {
 		operator := GetClosestOperatorVersion(opsetID, operatorVersions)
 		if operator == nil {