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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 open_local_file(self, url):
 """Use local file."""

        import future.backports.email.utils as email_utils
        import mimetypes
        host, file = splithost(url)
        localname = url2pathname(file)
        try:
            stats = os.stat(localname)
        except OSError as e:
            raise URLError(e.strerror, e.filename)
        size = stats.st_size
        modified = email_utils.formatdate(stats.st_mtime, usegmt=True)
        mtype = mimetypes.guess_type(url)[0]
        headers = email.message_from_string(
            'Content-Type: %s\nContent-Length: %d\nLast-modified: %s\n' %
            (mtype or 'text/plain', size, modified))
        if not host:
            urlfile = file
            if file[:1] == '/':
                urlfile = 'file://' + file
            return addinfourl(open(localname, 'rb'), headers, urlfile)
        host, port = splitport(host)
        if (not port
           and socket.gethostbyname(host) in ((localhost(),) + thishost())):
            urlfile = file
            if file[:1] == '/':
                urlfile = 'file://' + file
            elif file[:2] == './':
                raise ValueError("local file url may start with / or file:. Unknown url of type: %s" % url)
            return addinfourl(open(localname, 'rb'), headers, urlfile)
        raise URLError('local file error: not on local host')