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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 reset_index(self, inplace=True, drop=True):
 """ Flattens the grouped data structure. #TODO: The parameters here are meaningless Flattens the grouped data structure. What is returned is a DataFrameWeld object. """

        if len(self.column_types) == 1:
            vectype = self.column_types[0]
            if isinstance(vectype, WeldVec):
                elem_type = vectype.elemType
                if isinstance(elem_type, WeldStruct):
                    self.column_types = elem_type.field_types
                    value_type = WeldStruct(self.column_types)
                else:
                    self.column_types = elem_type
                    value_type = elem_type
                if len(self.grouping_column_types) == 1:
                    group_type = self.grouping_column_types[0]
                else:
                    group_type = WeldStruct(self.grouping_column_types)

                self.weld_type = WeldStruct([group_type, value_type])
                self.expr = grizzly_impl.flatten_group(
                    self.expr,
                    self.column_types,
                    self.grouping_column_types
                )