Return the Tcl/Tk patch level as a named tuple with the same five fields as sys.version_info: major, minor, micro, releaselevel and serial. releaselevel is 'alpha', 'beta' or 'final'. Converting it to a string gives the version in the usual Tcl/Tk notation, for example '9.0.3' for a final release or '9.1b2' for a pre-release.