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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 size(self):
 """Calculate and return the file size in bytes."""

        old = self.__file.tell()        # old position

        self.__file.seek(0, 2)          # end of file
        n_bytes = self.__file.tell()    # file size in bytes

        self.__file.seek(old)           # back to old position

        return n_bytes