If you get an error message stating that python3 is not found, you will need to install it (most modern UNIX-like OSes provide Python 3 as part of the default install). To install you will need to use sudo yum install python3, sudo apt install python3, or brew install python3 as appropriate. On the Mac you may get an error message like:
python3 get.py Platform: x86_64-apple-darwin Downloading python3-macosx-placeholder.tar.gz Traceback (most recent call last): File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/urllib/request.py", line 1317, in do_open encode_chunked=req.has_header('Transfer-encoding')) ... File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/ssl.py", line 1117, in do_handshake self._sslobj.do_handshake() ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1056)This is because Homebrew on the Mac does not always install the required SSL certificates by default. Install them manually (adjust the Python 3.7 as needed) with:
cd "/Applications/Python 3.7/" && sudo "./Install Certificates.command"