expected_node_occurrence: a dict from NodeSpec to
                        expected number of occurences (int)
                        e.g. {NodeSpec.call_function(torch.quantize_per_tensor) : 1,
                                NodeSpec.call_method('dequantize'): 1}
                    expected_node_list: a list of NodeSpec, used to check the order
                        of the occurrence of Node
                        e.g. [NodeSpec.call_function(torch.quantize_per_tensor),
                                NodeSpec.call_module(nnq.Conv2d),
                                NodeSpec.call_function(F.hardtanh_),
                                NodeSpec.call_method('dequantize')]
                    is_reference: if True, enables reference mode
                    print_debug_info: if True, prints debug info
                    custom_qconfig_dict: overrides default qconfig_dict
                    prepare_expected_node: same as expected_node, but for prepare
                    prepare_expected_node_occurrence: same as
                        expected_node_occurrence, but for prepare
                    prepare_expected_node_list: same as expected_node_list, but
                        for prepare

                Returns:
                    A dictionary with the following structure:
                   {
                       "prepared": ...,  # the prepared model
                       "quantized": ...,  # the quantized non-reference model
                       "quantized_reference": ...,  # the quantized reference model
                       "result": ...,  # the result for either quantized or
                                       # quantized_reference model depending on the
                                       # is_reference arguemnt
                   }
            r