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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 pick(self, filenames: Iterable[str]) -> str: """Pick one filename based on priority rules."""

        filenames = sorted(filenames, reverse=True)  # e.g., v2 before v1
        for priority in sorted(self.rules.keys(), reverse=True):
            patterns = self.rules[priority]
            for pattern in patterns:
                for filename in filenames:
                    if pattern.search(filename):
                        return filename
        return filenames[0]