
**Apache Airflow version**:

master

**What happened**:

https://github.com/apache/airflow/blob/master/airflow/models/baseoperator.py#L356 --> should be timedelta not datetime


airflow/models/baseoperator.py
"""Base metaclass of BaseOperator."""
    def __call__(cls, *args, **kwargs):
        """
        Called when you call BaseOperator(). In this way we are able to perform an action
        after initializing an operator no matter where  the ``super().__init__`` is called
        (before or after assign of new attributes in a custom operator).
        """
        obj: BaseOperator = type.__call__(cls, *args, **kwargs)
        
        obj.set_xcomargs_dependencies()
        
        obj._BaseOperator__instantiated = True
        return obj
@functools.total_ordering
class BaseOperator(Operator, LoggingMixin, TaskMixin, metaclass=BaseOperatorMeta):
    """
    Abstract base class for all operators. Since operators create objects that
    become nodes in the dag, BaseOperator contains many recursive methods for