def _move_and_merge_tree(src, dst):
    """
    Move src directory to dst, if dst is already exists,
    merge src to dst
    """
    if not osp.exists(dst):
        shutil.move(src, dst)
    elif osp.isfile(src):
        shutil.move(src, dst)
    else:
        for fp in os.listdir(src):
            src_fp = osp.join(src, fp)
            dst_fp = osp.join(dst, fp)
            if osp.isdir(src_fp):
                if osp.isdir(dst_fp):
                    _move_and_merge_tree(src_fp, dst_fp)
                else:
                    shutil.move(src_fp, dst_fp)
            elif osp.isfile(src_fp) and \
                    not osp.isfile(dst_fp):
                shutil.move(src_fp, dst_fp)

    Move src directory to dst, if dst is already exists,
    merge src to dst
    
deploy/pipeline/download.py