code: def _deserialize(self, value, attr, obj):
          
          if value is None:
              return None
  
          try:
              attribute_elements = [attr_element.split(",") for attr_element in obj.getlist(attr)]
              attribute_params = [param for attr_param in attribute_elements for param in attr_param]
  
              return PrintableList(super(QueryStringList, self)._deserialize(attribute_params, attr, obj))
          except ValueError:
              raise ValidationError("Invalid query string list argument")
docs: _deserialize handles multiple formats of query string parameter lists
          including:
  
          /foo?bars=1,2
          /foo?bars[]=1&bars[]2
  
          and returns a list of values