+ @classmethod
+ def total_effort_at_date(cls, db_conn: DatabaseConnection, date: str
+ ) -> float:
+ """Sum all .performed_effort of Todos at Day of date."""
+ total_effort = 0.0
+ days_todos = cls.by_date(db_conn, date)
+ for todo in days_todos:
+ total_effort += todo.performed_effort
+ return total_effort
+