Error installing

I tried installing taichi through pip. It shows the below error message constantly.

python3 -m pip install taichi-nightly

ERROR: Could not find a version that satisfies the requirement taichi-nightly (from versions: none)

ERROR: No matching distribution found for taichi-nightly

My python environment is as follows:

Python 3.6.6 |Anaconda, Inc.| (default, Jun 28 2018, 11:07:29)

[GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)] on darwin

Type “help”, “copyright”, “credits” or “license” for more information.

Thanks for reporting this issue. Are you using a non-official PyPI source?

I’m not sure what “official PyPI” means. I’m using a separate pip, though.