Python is a modern, general-purpose, high-level language developed by Guido van Rossum as a result of his work with the ABC programming language. Python's philosophy is pragmatic; its users often speak of the Zen of Python, strongly preferring a single obvious way to accomplish any task. Ports exist for VMs such as Microsoft's CLR and the JVM, but the primary implementation is CPython, still developed by van Rossum and other volunteers, who just released Python 3.0, a backward-incompatible rethinking of parts of the language and its core libraries.