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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 getcells(self, line):
        '''Using self.boundaries, extract cells from the given line.
        '''
        for boundary in self.boundaries:
            cell = line.lstrip()[boundary].strip()
            if cell:
                for cell in re.split('\s{3,}', cell):
                    yield cell
            else:
                yield None