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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 push(self, remote=None, revision=None):
 """ Push changes from the local repository to a remote repository. :param remote: The location of a remote repository (a string or :data:`None`). :param revision: A specific revision to push (a string or :data:`None`). .. warning:: Depending on the version control backend the push command may fail when there are no changes to push. No attempt has been made to make this behavior consistent between implementations (although the thought has crossed my mind and I'll likely revisit this in the future). """

        # Make sure the local repository exists.
        self.ensure_exists()
        # Make sure there is a remote repository to push to.
        if not (remote or self.remote or self.default_push_remote):
            logger.info("Skipping push (no default remote is configured).")
        # Push the changes to the remote repository.
        timer = Timer()
        logger.info("Pushing changes from %s to %s ..",
                    format_path(self.local),
                    remote or self.remote or "default remote")
        self.context.execute(*self.get_push_command(remote, revision))
        logger.debug("Took %s to push changes to remote repository.", timer)