set_primary_sim_slot
Description:
[ Version ( since = "1.16" ) ]
public async bool set_primary_sim_slot (uint sim_slot, Cancellable? cancellable) throws Error
  public async bool set_primary_sim_slot (uint sim_slot, Cancellable? cancellable) throws Error
Asynchronously requests to select which SIM slot to be considered as primary.
When the operation is finished, callback will be invoked in the thread-default main loop of the thread you are calling this
      method from. You can then call set_primary_sim_slot.end to get the result of the operation.
See set_primary_sim_slot_sync for the synchronous, blocking version of this method.
Parameters:
| this | A Modem. | 
| sim_slot | SIM slot number. | 
| cancellable | A Cancellable or  | 
| callback | A TaskReadyCallback to call when the request is satisfied or  | 
| user_data | User data to pass to  |