docs: 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