Crate pyenv_python

Functions

pyenv_python_path	Returns the python path as determined by pyenv. Returns None if pyenv isn't setup correctly.
pyenv_root	Returns what $(pyenv root) would return. That is, $PYENV_ROOT or $HOME/.pyenv if they exist
pyenv_version	Returns the current pyenv version as determined by https://github.com/pyenv/pyenv#choosing-the-python-version. If none is found, then None is returned.
python_path	Get the path of python using pyenv, i.e., using pyenv_version(). If pyenv_version() returns None, then the system python is used, i.e. $PATH.
system_python_path	Returns the system python on $PATH, excluding this program (when run as python). If pyenv is installed, then $PYENV_ROOT/shims/python is skipped, too. Otherwise, an infinite loop would be formed between ourselves and $PYENV_ROOT/shims/python.