def load(self):
        # type: () -> None
        """Loads configuration from configuration files and environment
        """
        self._load_config_files()
        if not self.isolated:
            self._load_environment_vars()
Loads configuration from configuration files and environment
        
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_internal/configuration.py