Assigning dict to class variable converts it to tuple

I’ve been using python for a while and I’ve never run into this.

I am passing a dict to a class and assigning it to a class variable like so.

class Validator(ABC):
    def __init__(self, available_messages, rule_list: dict, data) -> None:
        self.available_messages = available_messages,
        self.rule_list: dict = rule_list,      
        self.data = data
        self.messages = []
        self.validate()

If I print the type of rule_list prior to assigning it to self.rule_list I get <class 'dict'>. Immedietly after assignment, I get <class 'tuple'>.

I want to keep rule_list as a dictionary. What am I doing wrong?

Thanks

Answer

The problem is the comma at the end of the Line, making it a tuple