pip install SimpleITK scikit-image

报错：

ERROR: Exception:
Traceback (most recent call last):
File "/home/aistudio/.data/webide/pip/lib/python3.7/site-packages/pip/_internal/cli/base_command.py", line 167, in exc_logging_wrapper
status = run_func(*args)
File "/home/aistudio/.data/webide/pip/lib/python3.7/site-packages/pip/_internal/cli/req_command.py", line 205, in wrapper
return func(self, options, args)
File "/home/aistudio/.data/webide/pip/lib/python3.7/site-packages/pip/_internal/commands/install.py", line 336, in run
use_pep517=options.use_pep517,
File "/home/aistudio/.data/webide/pip/lib/python3.7/site-packages/pip/_internal/cli/req_command.py", line 337, in make_resolver
import pip._internal.resolution.resolvelib.resolver
File "/home/aistudio/.data/webide/pip/lib/python3.7/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 17, in
from pip._internal.resolution.resolvelib.provider import PipProvider
File "/home/aistudio/.data/webide/pip/lib/python3.7/site-packages/pip/_internal/resolution/resolvelib/provider.py", line 18, in
from .factory import Factory
File "/home/aistudio/.data/webide/pip/lib/python3.7/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 61, in
from .found_candidates import FoundCandidates, IndexCandidateInfo
ValueError: source code string cannot contain null bytes

（有一段时间自己好了，现在一直这样了）