def Norm(self, setter):<EOL>
return self._compose_optic(optics.NormalisingIso(setter))<EOL>
An isomorphism that applies a function as it sets a new
        focus without regard to the old state. It will get foci without
        transformation. This lens allows you to pre-process values before
        you set them, but still get values as they exist in the state.
        Useful for type conversions or normalising data.

        For best results, your normalisation function should be
        idempotent.  That is, applying the function twice should have
        no effect::

            setter(setter(value)) == setter(value)

        Equivalent to `Isomorphism((lambda s: s), setter)`.

            >>> from lenses import lens
            >>> def real_only(num):
            ...     return num.real
            ...
            >>> lens.Norm(real_only)
            UnboundLens(NormalisingIso(<function real_only at ...>))
            >>> lens[0].Norm(real_only).get()([1.0, 2.0, 3.0])
            1.0
            >>> lens[0].Norm(real_only).set(4+7j)([1.0, 2.0, 3.0])
            [4.0, 2.0, 3.0]

        Types with constructors that do conversion are often good targets
        for this lens:

            >>> lens[0].Norm(int).set(4.0)([1, 2, 3])
            [4, 2, 3]
            >>> lens[1].Norm(int).set('5')([1, 2, 3])
            [1, 5, 3]