lambda string builder

class Action:
    def __init__(self, val1: str, val2: str):
        self._one = val1
        self._two = val2
        
    def to_str(self):
        ret = {
            "key1": self._one,
            "key2": self._two
        }
        
        return str(ret)

act_1 = Action(val1="boo", val2="hoo")
act_2 = Action(val1="foo", val2="bar")
actions = []
actions.append(act_1)
actions.append(act_2)

data = {
        "actions": list(map(lambda action: f"{action.to_str()},", actions)),
    }

print(data)

# expect

# {'actions': ["{'key1': 'boo', 'key2': 'hoo'},", "{'key1': 'foo', 'key2': 'bar'},"]}