def install():
    """Manual install main script.
    """
    # check installed package
    print("Compare to '%s' ..." % _DST)
    need_install_flag = check_need_install()
    if not need_install_flag:
        print("\tpackage is up-to-date, no need to install.")
        return
    print("Difference been found, start installing ...")

    # remove __pycache__ folder and *.pyc file
    print("Remove *.pyc file ...")
    pyc_folder_list = list()
    for root, _, basename_list in os.walk(_ROOT):
        if os.path.basename(root) == "__pycache__":
            pyc_folder_list.append(root)

    for folder in pyc_folder_list:
        shutil.rmtree(folder)
    print("\tall *.pyc file has been removed.")

    # install this package to all python version
    print("Uninstall %s from %s ..." % (_PACKAGE_NAME, _DST))
    try:
        shutil.rmtree(_DST)
        print("\tSuccessfully uninstall %s" % _PACKAGE_NAME)
    except Exception as e:
        print("\t%s" % e)

    print("Install %s to %s ..." % (_PACKAGE_NAME, _DST))
    shutil.copytree(_ROOT, _DST)
    print("\tComplete!")
Manual install main script.