def interpreter_name():
    # type: () -> str
    """
    Returns the name of the running interpreter.
    """
    try:
        name = sys.implementation.name  # type: ignore
    except AttributeError:  # pragma: no cover
        # Python 2.7 compatibility.
        name = platform.python_implementation().lower()
    return INTERPRETER_SHORT_NAMES.get(name) or name

    Returns the name of the running interpreter.
    
src/pkg_resources/_vendor/packaging/tags.py