需要帮助处理python 2.7和python 3上的beautifulsoup错误

我正在尝试设置BeautifulSoup4，以便可以运行以下命令：

from bs4 import BeautifulSoup

但是，当我安装BeautifulSoup4时，得到以下信息：

Defaulting to user installation because normal site-packages is not writeable. 
Requirement already satisfied: beautifulsoup4 in ./Library/Python/2.7/lib/python/site-packages (4.8.2)
Requirement already satisfied: soupsieve>=1.2 in ./Library/Python/2.7/lib/python/site-packages (from beautifulsoup4) (1.9.5)
Requirement already satisfied: backports.functools-lru-cache; python_version < "3" in ./Library/Python/2.7/lib/python/site-packages (from soupsieve>=1.2->beautifulsoup4) (1.6.1)

$ from bs4 import BeautifulSoup4
from: can't read /var/mail/bs4

在Python3中运行时，出现此错误

Python 3.8.2 
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from bs4 import beautifulsoup4
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'beautifulsoup4' from 'bs4' (/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/bs4/__init__.py)

我的计算机上同时装有Python 3和Python 2.7，但无法弄清楚如何识别bs4

欣赏建议！

问题来源：stackoverflow