What kind of variable is this? (Python Lambda Function)

[Mark Richardson]

A piece of code within a lambda function on AWS which never made sense to me:

if(end_index > len(payer_list_split)):            logger.info('end_index: {}, start_index :{}, len(payer_list_split) {}'.format(end_index,start_index, len(payer_list_split)))            end_index = len(payer_list_split)            is_last_batch = True        request_items = create_scheduler_batch_write_structure(table_name, payer_batch,header, is_last_batch)        logger.info(request_items)        response = dynamoDb.batch_write_item(            RequestItems=request_items        )
The last line (line #8) where it says: `RequestItems=request_items`
What kind of variable is "RequestItems?"
And why does it show up as "red" (as if it's an error something) within an IDE, such as IntelliJ?

[Stephan van Hulst]

It's a so called "keyword argument", but this is an absolutely terrible name, so I will call them "named argument" instead.

When you call a function in python, you can explicitly name the parameter that you want to assign an argument to.

RequestItems is a parameter of the batch_write_item function, and you're naming it explicitly when assigning request_items to it.

[Rob Spoor]

It's a great way to handle multiple optional arguments. Suppose you have a method like this:
def my_method(self, required1, required2, optional1 = None, optional2 = 0, optional3 = False):    pass
You need to pass the first two required arguments, but if you want to additionally only use a non-default value for the third optional, you call it like this:
# don't repeat the defaults for the first two optional arguments # equivalent to x.my_method(1, "", None, 0, True) x.my_method(1, "", optional3 = True)