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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 add(self, element):
 """ Add a new element or list of elements to this cell. Parameters element : object, list The element or list of elements to be inserted in this cell. Returns ------- out : ``Cell`` This cell. """

        if isinstance(element, list):
            for e in element:
                if isinstance(e, Label):
                    self.labels.append(e)
                else:
                    self.elements.append(e)
        else:
            if isinstance(element, Label):
                self.labels.append(element)
            else:
                self.elements.append(element)
        self._bb_valid = False
        return self