Python：相对导入

我正在尝试使用具有以下结构的包：

文件 prova.py 仅包含以下行：

import bipartite_class

而 bipartite_class.py 具有以下初始行：

from .nes import *
from .mod import *
from .graphs import *
from .contrib import *
from .null import *
from .tests import *

from getref import *

import pickle
import tempfile
import os
import numpy as np
import networkx as nx

import os.path

当我尝试编译 prova.py 时，出现以下错误：

Traceback (most recent call last):
  File "prova.py", line 1, in <module>
    import bipartite_class
  File "/Desktop/CD_BEST/Bipartito/bipy-master/bipy/bipartite_class.py", line 1, in <module>
    from .nes import *
ValueError: Attempted relative import in non-package

如果我尝试删除 bipartite_class.py 中的点，我会得到：

Traceback (most recent call last):
  File "prova.py", line 1, in <module>
    import bipartite_class
  File "/Desktop/CD_BEST/Bipartito/bipy-master/bipy/bipartite_class.py", line 1, in <module>
    from nes import *
  File "/Desktop/CD_BEST/Bipartito/bipy-master/bipy/nes/_init_.py", line 5, in <module>
    from nodf import *
  File "/Desktop/CD_BEST/Bipartito/bipy-master/bipy/nes/nodf.py", line 3, in <module>
    from ..mainfuncs import *
ValueError: Attempted relative import beyond toplevel package

我该怎么办？