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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 _normalize_file_paths(self, *args):
 """Returns all given configuration file paths as one list."""

        paths = []
        for arg in args:
            if arg is None:
                continue
            elif self._is_valid_file(arg):
                paths.append(arg)
            elif isinstance(arg, list) and all(self._is_valid_file(_) for _ in arg):
                paths = paths + arg
            elif not self.ignore_errors:
                raise TypeError('Config file paths must be string path or list of paths!')
        return paths