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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 get_ipv6fs_table(self):
 """Returns global IPv6 Flow Specification table. Creates the table if it does not exist. """

        ipv6fs_table = self._global_tables.get(RF_IPv6_FLOWSPEC)
        # Lazy initialization of the table.
        if not ipv6fs_table:
            ipv6fs_table = IPv6FlowSpecTable(self._core_service,
                                             self._signal_bus)
            self._global_tables[RF_IPv6_FLOWSPEC] = ipv6fs_table
            self._tables[(None, RF_IPv6_FLOWSPEC)] = ipv6fs_table

        return ipv6fs_table