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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 groups(self):
 """Return an iterator that spans values with group and variable names. Elements of the iterator consist of a tuple containing two values. The first is internal tuple containing the current namelist group and its variable name. The second element of the returned tuple is the value associated with the current group and variable. """

        for key, value in self.items():
            for inner_key, inner_value in value.items():
                yield (key, inner_key), inner_value