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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 check_exists_repositories(repo):
 """Checking if repositories exists by PACKAGES.TXT file """

    pkg_list = "PACKAGES.TXT"
    if repo == "sbo":
        pkg_list = "SLACKBUILDS.TXT"
    if check_for_local_repos(repo) is True:
        pkg_list = "PACKAGES.TXT"
        return ""
    if not os.path.isfile("{0}{1}{2}".format(
            _meta_.lib_path, repo, "_repo/{0}".format(pkg_list))):
        return repo
    return ""