所以我尝试使用以下命令从 PyPI 安装一个包：
sudo pip3 install switcheo
但最终安装包失败。
Error checking for conflicts.
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2584, in version
return self._version
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2691, in __getattr__
raise AttributeError(attr)
AttributeError: _version
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip/_internal/commands/install.py", line 503, in _warn_about_conflicts
package_set, _dep_info = check_install_conflicts(to_install)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip/_internal/operations/check.py", line 108, in check_install_conflicts
package_set, _ = create_package_set_from_installed()
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/pip/_internal/operations/check.py", line 47, in create_package_set_from_installed
package_set[name] = PackageDetails(dist.version, dist.requires())
File …