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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 is_draft_version(self):
 """ Return if this version is the draft version of a layer """

        pub_ver = getattr(self, 'published_version', None)
        latest_ver = getattr(self, 'latest_version', None)
        this_ver = getattr(self, 'this_version', None)
        return this_ver and latest_ver and (this_ver == latest_ver) and (latest_ver != pub_ver)