def METHOD_NAME(t: tuple) -> str:
    """
    Convert tuple of 2 (3) integers into string in the form ``xx`` (``xyz``).
    Assume C-indexing e.g. 0 --> x
    >>> assert itup2s((0, 1)) == "xy"
    >>> assert itup2s((0, 1, 2)) == "xyz"
    """
    if not isinstance(t, tuple) and len(t) not in (2, 3):
        raise TypeError("Expecting tuple of len 2 or 3, got %s" % str(t))
    d = {0: "x", 1: "y", 2: "z"}
    return "".join(d[i] for i in t)