get_metadata_item
  
  Description:
  [ 
Version ( since = 
"0.1.28" ) ]
public unowned string get_metadata_item (
string key)
  
    Returns the sensor metadata for a specific key.
    Parameters:
    
      
        | this | a Sensor instance. | 
      
        | key | a key for the metadata dictionary | 
    
    Returns:
    
      
        | the metadata value, or null if not set. |