MyPy from github master, Python 3.9

a.sh

PS1='\`\`\`
\`\`\`bash
$ '
python3.9 -m venv venv
venv/bin/pip install --upgrade pip setuptools wheel
venv/bin/pip install git+https://github.com/python/mypy/
mypyc --help
venv/bin/mypyc --help

b.md

$ python3.9 -m venv venv

$ venv/bin/pip install --upgrade pip setuptools wheel
Collecting pip
  Using cached pip-20.3.3-py2.py3-none-any.whl (1.5 MB)
Collecting setuptools
  Using cached setuptools-51.1.2-py3-none-any.whl (784 kB)
Collecting wheel
  Using cached wheel-0.36.2-py2.py3-none-any.whl (35 kB)
Installing collected packages: pip, setuptools, wheel
  Attempting uninstall: pip
    Found existing installation: pip 20.2.3
    Uninstalling pip-20.2.3:
      Successfully uninstalled pip-20.2.3
  Attempting uninstall: setuptools
    Found existing installation: setuptools 49.2.1
    Uninstalling setuptools-49.2.1:
      Successfully uninstalled setuptools-49.2.1
Successfully installed pip-20.3.3 setuptools-51.1.2 wheel-0.36.2

$ venv/bin/pip install git+https://github.com/python/mypy/
Collecting git+https://github.com/python/mypy/
  Cloning https://github.com/python/mypy/ to /tmp/pip-req-build-lemv9064
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
    Preparing wheel metadata ... done
Collecting mypy-extensions<0.5.0,>=0.4.3
  Using cached mypy_extensions-0.4.3-py2.py3-none-any.whl (4.5 kB)
Collecting typed-ast<1.5.0,>=1.4.0
  Using cached typed_ast-1.4.2-cp39-cp39-manylinux1_x86_64.whl (769 kB)
Collecting typing-extensions>=3.7.4
  Using cached typing_extensions-3.7.4.3-py3-none-any.whl (22 kB)
Building wheels for collected packages: mypy
  Building wheel for mypy (PEP 517) ... done
  Created wheel for mypy: filename=mypy-0.800+dev.92923b2ed8085a38c353382f805c9e2e8716e717-py3-none-any.whl size=2514733 sha256=7718c96b14a1064849fa7b25a53236248c96815aef86f96a60c37ddcd82e792d
  Stored in directory: /tmp/pip-ephem-wheel-cache-wd7d9tag/wheels/d4/70/e1/cf43b63d116cc20fcce5aa34f12e81f9c3273e51a6af6a7e2d
Successfully built mypy
Installing collected packages: typing-extensions, typed-ast, mypy-extensions, mypy
Successfully installed mypy-0.800+dev.92923b2ed8085a38c353382f805c9e2e8716e717 mypy-extensions-0.4.3 typed-ast-1.4.2 typing-extensions-3.7.4.3

$ mypyc --help
zsh: command not found: mypyc