def METHOD_NAME():
    """Return abbreviated implementation name."""
    impl = platform.python_implementation()
    if impl == 'PyPy':
        return 'pp'
    elif impl == 'Jython':
        return 'jy'
    elif impl == 'IronPython':
        return 'ip'
    elif impl == 'CPython':
        return 'cp'
    raise LookupError('Unknown Python implementation: ' + impl)