docs: def pkg_upgrade(repo, skip, flag):
      """Checking packages for upgrade
      """
      Msg().checking()
      PACKAGES_TXT = RepoInit(repo).fetch()[0]
      pkgs_for_upgrade = []
      # name = data[0]
      # location = data[1]
      # size = data[2]
      # unsize = data[3]
      data = repo_data(PACKAGES_TXT, repo, flag="")
      for pkg in installed():
          status(0.0005)
          inst_pkg = split_package(pkg)
          for name in data[0]:
              if name:    # this tips because some pkg_name is empty
                  repo_pkg = split_package(name[:-4])
              if (repo_pkg[0] == inst_pkg[0] and
                  LooseVersion(repo_pkg[1]) > LooseVersion(inst_pkg[1]) and
                  repo_pkg[3] >= inst_pkg[3] and
                      inst_pkg[0] not in skip and
                      repo_pkg[1] != "blacklist"):
                  pkgs_for_upgrade.append(repo_pkg[0])
      Msg().done()
      if "--checklist" in flag:
          pkgs_for_upgrade = choose_upg(pkgs_for_upgrade)
      return pkgs_for_upgrade