'Return list of registry keys.'

def read_keys(cls, base, key):

    try:
        handle = RegOpenKeyEx(base, key)
    except RegError:
        return None
    L = []
    i = 0
    while True:
        try:
            k = RegEnumKey(handle, i)
        except RegError:
            break
        L.append(k)
        i += 1
    return L
