anslate(0.4, 0.6)
            >>> t2 = Identity.translate(0.08, 0.18).scale(0.2, 0.3)
            >>> t1
            <Transform [0.2 0 0 0.3 0.08 0.18]>
            >>> t2
            <Transform [0.2 0 0 0.3 0.08 0.18]>
            >>> t1 == t2
            0

    Transform instances are hashable, meaning you can use them as
    keys in dictionaries::

            >>> d = {Scale(12, 13): None}
            >>> d
            {<Transform [12 0 0 13 0 0]>: None}

    But again, beware of floating point rounding errors::

            >>> t1 = Identity.scale(0.2, 0.3).translate(0.4, 0.6)
            >>> t2 = Identity.translate(0.08, 0.18).scale(0.2, 0.3)
            >>> t1
            <Transform [0.2 0 0 0.3 0.08 0.18]>
            >>> t2
            <Transform [0.2 0 0 0.3 0.08 0.18]>
            >>> d = {t1: None}
            >>> d
            {<Transform [0.2 0 0 0.3 0.08 0.18]>: None}
            >>> d[t2]
            Traceback (most recent call last):
              File "<stdin>", line 1, in ?
            KeyError: <Transform [0.2 0 0 0.3 0.08 0.18]>
    r