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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 append(self, data):
 """Append rows to an existing CSV file."""

        # CSV file exists, append rows
        if os.path.exists(self.file_path):
            return self.write(data, method='a')
        # CSV file does NOT exist, create new file and write rows
        else:
            return self.write(data, method='w')