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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 cache_dir(self, path, saltenv='base', include_empty=False,
                  include_pat=None, exclude_pat=None, cachedir=None):
        '''
        Download all of the files in a subdir of the master
        '''
        ret = []

        path = self._check_proto(salt.utils.data.decode(path))
        # We want to make sure files start with this *directory*, use
        # '/' explicitly because the master (that's generating the
        # list of files) only runs on POSIX
        if not path.endswith('/'):
            path = path + '/'

        log.info(
            'Caching directory \'%s\' for environment \'%s\'', path, saltenv
        )
        # go through the list of all files finding ones that are in
        # the target directory and caching them
        for fn_ in self.file_list(saltenv):
            fn_ = salt.utils.data.decode(fn_)
            if fn_.strip() and fn_.startswith(path):
                if salt.utils.stringutils.check_include_exclude(
                        fn_, include_pat, exclude_pat):
                    fn_ = self.cache_file(
                        salt.utils.url.create(fn_), saltenv, cachedir=cachedir)
                    if fn_:
                        ret.append(fn_)

        if include_empty:
            # Break up the path into a list containing the bottom-level
            # directory (the one being recursively copied) and the directories
            # preceding it
            # separated = string.rsplit(path, '/', 1)
            # if len(separated) != 2:
            #     # No slashes in path. (So all files in saltenv will be copied)
            #     prefix = ''
            # else:
            #     prefix = separated[0]
            cachedir = self.get_cachedir(cachedir)

            dest = salt.utils.path.join(cachedir, 'files', saltenv)
            for fn_ in self.file_list_emptydirs(saltenv):
                fn_ = salt.utils.data.decode(fn_)
                if fn_.startswith(path):
                    minion_dir = '{0}/{1}'.format(dest, fn_)
                    if not os.path.isdir(minion_dir):
                        os.makedirs(minion_dir)
                    ret.append(minion_dir)
        return ret