[DOCS] Improving code snippets for quantization

docs/optimization_guide/nncf/ptq/code/ptq_onnx.py

@@ -16,7 +16,8 @@ def transform_fn(data_item):
 #! [dataset]
 
 #! [quantization]
-model = ... # onnx.ModelProto object
+import onnx
+model = onnx.ModelProto() # onnx.ModelProto object
 
 quantized_model = nncf.quantize(model, calibration_dataset)
 #! [quantization]

docs/optimization_guide/nncf/ptq/code/ptq_openvino.py

@@ -15,7 +15,8 @@ def transform_fn(data_item):
 #! [dataset]
 
 #! [quantization]
-model = ... # openvino.runtime.Model object
+import openvino as ov
+model = ov.Model() # openvino.runtime.Model object
 
 quantized_model = nncf.quantize(model, calibration_dataset)
 #! [quantization]

docs/optimization_guide/nncf/ptq/code/ptq_tensorflow.py

@@ -15,7 +15,8 @@ def transform_fn(data_item):
 #! [dataset]
 
 #! [quantization]
-model = ... # tensorflow.Module object
+import tensorflow as tf
+model = tf.Module() # tensorflow.Module object
 
 quantized_model = nncf.quantize(model, calibration_dataset)
 #! [quantization]

docs/optimization_guide/nncf/ptq/code/ptq_torch.py

@@ -15,7 +15,8 @@ def transform_fn(data_item):
 #! [dataset]
 
 #! [quantization]
-model = ... # torch.nn.Module object
+import torch.nn as nn
+model = nn.Module() # torch.nn.Module object
 
 quantized_model = nncf.quantize(model, calibration_dataset)
 #! [quantization]