macOS 10.15.5，安装正常，但导入失败，提示TAICHI_REPO_DIR不存在。论坛中没看到类似的问题，请问如何解决？
In [1]: import taichi as ti
[Taichi] mode=development
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-1-a49150b41477> in <module>
----> 1 import taichi as ti
~/anaconda3/envs/ti/lib/python3.8/site-packages/taichi/__init__.py in <module>
1 from taichi.main import main
----> 2 from taichi.core import ti_core
3 from taichi.core import start_memory_monitoring, is_release, package_root
4 from taichi.misc.util import vec, veci, set_gdb_trigger, set_logging_level, info, warn, error, debug, trace, INFO, WARN, ERROR, DEBUG, TRACE
5 from taichi.core.util import require_version
~/anaconda3/envs/ti/lib/python3.8/site-packages/taichi/core/__init__.py in <module>
----> 1 from .util import ti_core, build, format, load_module, start_memory_monitoring, \
2 is_release, package_root
3 from .unit import unit
4
5 ti_core.build = build
~/anaconda3/envs/ti/lib/python3.8/site-packages/taichi/core/util.py in <module>
283 print("[Taichi] mode=development")
284 if get_os_name() == 'osx':
--> 285 bin_dir = get_bin_directory()
286 os.environ['DYLD_FALLBACK_LIBRARY_PATH'] = get_runtime_directory()
287 lib_path = os.path.join(bin_dir, 'libtaichi_core.dylib')
~/anaconda3/envs/ti/lib/python3.8/site-packages/taichi/misc/settings.py in get_bin_directory()
50 else:
51 bin_rel_path = ['build']
---> 52 return os.path.join(get_repo_directory(), *bin_rel_path)
53
54
~/anaconda3/envs/ti/lib/python3.8/site-packages/taichi/misc/settings.py in get_repo_directory()
21 repo_dir = os.environ.get('TAICHI_REPO_DIR')
22 if not os.path.exists(repo_dir):
---> 23 raise ValueError(f"TAICHI_REPO_DIR [{repo_dir}] does not exist.")
24 return repo_dir
25
ValueError: TAICHI_REPO_DIR [/private/tmp/taichi] does not exist.