def get_system_environment(version): """ Return the first Python environment found for a string of the form 'X.Y' where X and Y are the major and minor versions of Python. :raises: :exc:`.InvalidPythonEnvironment` :returns: :class:`Environment` """ exe = which('python' + version) if exe: if exe == sys.executable: return SameEnvironment() return Environment(_get_python_prefix(exe), exe) if os.name == 'nt': for prefix, exe in _get_executables_from_windows_registry(version): return Environment(prefix, exe) raise InvalidPythonEnvironment("Cannot find executable python%s." % version)