def total_cost(self) -> Optional[float]:
        """
        Get the total estimated cost of this task.
        
        Returns:
            Optional[float]: The estimated cost in USD, or None if not available
        """
        the_total_cost = self.get_total_cost()
        if the_total_cost and "estimated_cost" in the_total_cost:
            return the_total_cost["estimated_cost"]
        return None

        Get the total estimated cost of this task.
        
        Returns:
            Optional[float]: The estimated cost in USD, or None if not available
        
src/upsonic/client/tasks/tasks.py