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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 _merge_raw(self, other):
 """For use with binary arithmetic."""

        if other is None:
            variables = OrderedDict(self.variables)
        else:
            # don't align because we already called xarray.align
            variables = expand_and_merge_variables(
                [self.variables, other.variables])
        return variables