code: def _GetPropertyValue(self, parser_mediator, properties, property_name):
      
      property_value = properties.get(property_name, None)
      if isinstance(property_value, py2to3.BYTES_TYPE):
        try:
          # TODO: get encoding form XML metadata.
          property_value = property_value.decode('utf-8')
        except UnicodeDecodeError:
          parser_mediator.ProduceExtractionWarning(
              'unable to decode property: {0:s}'.format(property_name))
  
      return property_value
docs: Retrieves a property value.
  
      Args:
        parser_mediator (ParserMediator): mediates interactions between parsers
            and other components, such as storage and dfvfs.
        properties (dict[str, object]): properties.
        property_name (str): name of the property.
  
      Returns:
        str: property value.