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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _assert_obj_type(pub, name="pub", obj_type=DBPublication):
 """ Make sure, that `pub` is instance of the `obj_type`. Args: pub (obj):
 Instance which will be checked. name (str):
 Name of the instance. Used in exception. Default `pub`. obj_type (class):
 Class of which the `pub` should be instance. Default :class:`.DBPublication`. Raises: InvalidType: When the `pub` is not instance of `obj_type`. """

    if not isinstance(pub, obj_type):
        raise InvalidType(
            "`%s` have to be instance of %s, not %s!" % (
                name,
                obj_type.__name__,
                pub.__class__.__name__
            )
        )