def get_manifest_selfLink(self, repo_name, digest=None):
url = "<STR_LIT>" % (self.base, repo_name)<EOL>if digest is None:<EOL><INDENT>digest = '<STR_LIT>'<EOL><DEDENT>return "<STR_LIT>" % (url, digest)<EOL>
get a selfLink for the manifest, for use by the client get_manifest
        function, along with the parents pull

       Parameters
       ==========
       repo_name: reference to the <username>/<repository>:<tag> to obtain
       digest: a tag or shasum version