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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 drop(self, labels, dim=None):
 """Drop variables or index labels from this dataset. Parameters labels : scalar or list of scalars Name(s) of variables or index labels to drop. dim : None or str, optional Dimension along which to drop index labels. By default (if ``dim is None``), drops variables rather than index labels. Returns ------- dropped : Dataset """

        if utils.is_scalar(labels):
            labels = [labels]
        if dim is None:
            return self._drop_vars(labels)
        else:
            try:
                index = self.indexes[dim]
            except KeyError:
                raise ValueError(
                    'dimension %r does not have coordinate labels' % dim)
            new_index = index.drop(labels)
            return self.loc[{dim: new_index}]