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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 read(self):
 """Reads data from the CSV file."""

        companies = []
        with open(self.file) as f:
            reader = unicodecsv.reader(f)
            for line in reader:
                if len(line) >= 1:
                    cnpj = self.format(line[0])
                    if self.valid(cnpj):
                        companies.append(cnpj)
        return companies