def METHOD_NAME():
    clp = os.environ.get('CLASSPATH')
    eip = get_config('EIDOSPATH')
    rep = get_config('REACHPATH')
    clp_parts = clp.split(':') if clp else []
    new_clp_parts = []
    has_eidos = False
    # Look at all the parts of the CLASSPATH
    for part in clp_parts:
        # If REACH is on the CLASSPATH, remove it
        if not rep or os.path.abspath(part) != rep:
            new_clp_parts.append(part)
        # If Eidos is not on the CLASSPATH, add it
        if eip and os.path.abspath(part) == eip:
            has_eidos = True
    if eip and not has_eidos:
        new_clp_parts.append(eip)
    # Set the new CLASSPATH
    new_clp = ':'.join(new_clp_parts)
    os.environ['CLASSPATH'] = new_clp