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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 make_input(self):
 """Construct and write the input file of the calculation."""

        # Set the file paths.
        all_files ={"ddkfile_" + str(n + 1): ddk for n, ddk in enumerate(self.ddk_filepaths)}
        all_files.update({"wfkfile": self.wfk_filepath})
        files_nml = {"FILES": all_files}
        files= nmltostring(files_nml)

        # Get the input specified by the user
        user_file = nmltostring(self.input.as_dict())

        # Join them.
        return files + user_file