def add_constructor(tag, object_constructor, Loader=None, constructor=Constructor):
    # type: (Any, Any, Any, Any) -> None
    """
    Add an object constructor for the given tag.
    object_onstructor is a function that accepts a Loader instance
    and a node object and produces the corresponding Python object.
    """
    if Loader is None:
        constructor.add_constructor(tag, object_constructor)
    else:
        if hasattr(Loader, 'add_constructor'):
            Loader.add_constructor(tag, object_constructor)
            return
        if issubclass(Loader, BaseLoader):
            BaseConstructor.add_constructor(tag, object_constructor)
        elif issubclass(Loader, SafeLoader):
            SafeConstructor.add_constructor(tag, object_constructor)
        elif issubclass(Loader, Loader):
            Constructor.add_constructor(tag, object_constructor)
        elif issubclass(Loader, RoundTripLoader):
            RoundTripConstructor.add_constructor(tag, object_constructor)
        else:
            raise NotImplementedError

    Add an object constructor for the given tag.
    object_onstructor is a function that accepts a Loader instance
    and a node object and produces the corresponding Python object.
    
dynaconf/vendor/ruamel/yaml/main.py