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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 current_version(self, object, relations_as_of=None, check_db=False):
 """ Return the current version of the given object. The current version is the one having its version_end_date set to NULL. If there is not such a version then it means the object has been 'deleted' and so there is no current version available. In this case the function returns None. Note that if check_db is False and object's version_end_date is None, this does not check the database to see if there is a newer version (perhaps created by some other code), it simply returns the passed object. ``relations_as_of`` is used to fix the point in time for the version; this affects which related objects are returned when querying for object relations. See ``VersionManager.version_as_of`` for details on valid ``relations_as_of`` values. :param Versionable object: object whose current version will be returned. :param mixed relations_as_of: determines point in time used to access relations. 'start'|'end'|datetime|None :param bool check_db: Whether or not to look in the database for a more recent version :return: Versionable """

        if object.version_end_date is None and not check_db:
            current = object
        else:
            current = self.current.filter(identity=object.identity).first()

        return self.adjust_version_as_of(current, relations_as_of)