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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def merge(self, datasets=None, separate_datasets=False):
 """This function merges datasets into one set."""

        self.logger.info("merging")
        if separate_datasets:
            warnings.warn("The option seperate_datasets=True is"
                          "not implemented yet. Performing merging, but"
                          "neglecting the option.")
        else:
            if datasets is None:
                datasets = list(range(len(self.datasets)))
            first = True
            for dataset_number in datasets:
                if first:
                    dataset = self.datasets[dataset_number]
                    first = False
                else:
                    dataset = self._append(dataset, self.datasets[dataset_number])
                    for raw_data_file, file_size in zip(self.datasets[dataset_number].raw_data_files,
                                                        self.datasets[dataset_number].raw_data_files_length):
                        dataset.raw_data_files.append(raw_data_file)
                        dataset.raw_data_files_length.append(file_size)
            self.datasets = [dataset]
            self.number_of_datasets = 1
        return self