get_priority
Description:
Retrieve one of the entries of the NMSettingVlan:ingress_priority_map or NMSettingVlan:egress_priority_map properties
      of this setting.
Parameters:
| this | 
           the SettingVlan  | 
      
| map | 
           the type of priority map  | 
      
| idx | 
           the zero-based index of the ingress/egress priority map entry  | 
      
| out_from | 
           on return the value of the priority map's 'from' item  | 
      
| out_to | 
           on return the value of priority map's 'to' item  | 
      
Returns:
| 
           
  |