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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_supported_connections(self):
 """Returns the number of supported simultaneous BLE connections. The BLED112 is capable of supporting up to 8 simultaneous BLE connections. However, the default firmware image has a limit of just 3 devices, which is a lot easier to run up against. This method retrieves the current value of this setting. Returns: int. The number of supported simultaneous connections, or -1 on error """

        if self.supported_connections != -1:
            return self.supported_connections
        
        if self.api is None:
            return -1

        self._set_state(self._STATE_DONGLE_COMMAND)
        self.api.ble_cmd_system_get_connections()
        self._wait_for_state(self._STATE_DONGLE_COMMAND)
        
        return self.supported_connections