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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 fetch(self, refspec=None, progress=None, **kwargs):
 """Fetch the latest changes for this remote :param refspec: A "refspec" is used by fetch and push to describe the mapping between remote ref and local ref. They are combined with a colon in the format <src>:<dst>, preceded by an optional plus sign, +. For example: git fetch $URL refs/heads/master:refs/heads/origin means "grab the master branch head from the $URL and store it as my origin branch head". And git push $URL refs/heads/master:refs/heads/to-upstream means "publish my master branch head as to-upstream branch at $URL". See also git-push(1). Taken from the git manual Fetch supports multiple refspecs (as the underlying git-fetch does) - supplying a list rather than a string for 'refspec' will make use of this facility. :param progress: See 'push' method :param kwargs: Additional arguments to be passed to git-fetch :return: information about the fetch results :note: As fetch does not provide progress information to non-ttys, we cannot make it available here unfortunately as in the 'push' method."""

        if refspec is None:
            # No argument refspec, then ensure the repo's config has a fetch refspec.
            self._assert_refspec()
        kwargs = add_progress(kwargs, self.repo.git, progress)
        if isinstance(refspec, list):
            args = refspec
        else:
            args = [refspec]

        proc = self.repo.git.fetch(self, *args, as_process=True, with_stdout=False,
                                   universal_newlines=True, v=True, **kwargs)
        res = self._get_fetch_info_from_stderr(proc, progress)
        if hasattr(self.repo.odb, 'update_cache'):
            self.repo.odb.update_cache()
        return res