Return the translation portion of the matrix as a vector.

        If out_vec is provided, store in out_vec instead of creating a new Vec3.

def get_trans(self, out_vec=None):
        """Return the translation portion of the matrix as a vector.

        If out_vec is provided, store in out_vec instead of creating a new Vec3.
        """

        if out_vec:
            return out_vec.set(*self.data[3][:3])

        return Vec3(*self.data[3][:3])