Building Boost with both Python 2 and 3 libraries on Windows 10

I'm on Windows 10 x64, I already unpacked "boost_1_69_0.7z" and ran "bootstrap.bat", however, when I compile it with "b2 toolset=msvc-14.16 --build-type=complete --abbreviate-paths architecture=x86 address-model=64 install -j4 --with-python python=2.7 --with-python python=3.6" I get this error message: "error: legal values: "3.6"".
How do I compile more Python libraries? In case that's not possible, how do I choose which Python version I want to use? In case I cannot choose anything else than "3.6" then why that command line option exists at all if there's no choice?
Thanks, I hope a solution exists.