M1で3.9未満のpythonを動かす

# Install x86 brew
arch -x86_64 /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"

# Install Python 3.7
arch -x86_64 /usr/local/bin/brew install python@3.7

# Add `python` executable (symlink to `python3`)
ln -s python3 "$(ibrew --prefix python@3.7)"/bin/python

# Symlink x86 Python 3.7 into pyenv
ln -s "$(ibrew --prefix python@3.7)" ~/.anyenv/envs/pyenv/versions/3.7.10

# Check
pyenv local 3.7.10
python -V
# Python 3.7.10
python -c 'import _ctypes' # works!