golden hour

/usr/local/lib/python3.6/site-packages/virtualenv/discovery

File/Folder	Size	Actions
__init__.py	0 B
__pycache__	-
builtin.py	5.99 KB
cached_py_info.py	6.2 KB
discover.py	1.12 KB
py_info.py	25.36 KB
py_spec.py	4.4 KB
windows	-

Edit: discover.py

from abc import ABCMeta, abstractmethod

class Discover(metaclass=ABCMeta):
    """Discover and provide the requested Python interpreter"""

@classmethod
    def add_parser_arguments(cls, parser):  # noqa: U100
        """Add CLI arguments for this discovery mechanisms.

:param parser: the CLI parser
        """
        raise NotImplementedError

def __init__(self, options):
        """Create a new discovery mechanism.

:param options: the parsed options as defined within :meth:`add_parser_arguments`
        """
        self._has_run = False
        self._interpreter = None
        self._env = options.env

@abstractmethod
    def run(self):
        """Discovers an interpreter.

:return: the interpreter ready to use for virtual environment creation
        """
        raise NotImplementedError

@property
    def interpreter(self):
        """
        :return: the interpreter as returned by :meth:`run`, cached
        """
        if self._has_run is False:
            self._interpreter = self.run()
            self._has_run = True
        return self._interpreter

__all__ = [
    "Discover",
]