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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 filenames(self) -> List[str]: """Names of the files contained in the the current working directory. Files names starting with underscores are ignored: ['file1.txt', 'file2.npy'] """

        return sorted(
            fn for fn in os.listdir(self.currentpath)
            if not fn.startswith('_'))