How to use the gwcs.coordinate_frames.CompositeFrame function in gwcs

def world_axis_physical_types(self):
        """
        An iterable of strings describing the physical type for each world axis.
        These should be names from the VO UCD1+ controlled Vocabulary
        (http://www.ivoa.net/documents/latest/UCDlist.html). If no matching UCD
        type exists, this can instead be ``"custom:xxx"``, where ``xxx`` is an
        arbitrary string.  Alternatively, if the physical type is
        unknown/undefined, an element can be `None`.
        """
        # A CompositeFrame orders the output correctly based on axes_order.
        if isinstance(self.output_frame, cf.CompositeFrame):
            return self.output_frame.axis_physical_types

        # If we don't have a CompositeFrame, where this is taken care of for us,
        # we need to make sure we re-order the output to match the transform.
        # The underlying frames don't reorder themselves because axes_order is global.
        return tuple(self.output_frame.axis_physical_types[i] for i in self.output_frame.axes_order)

return SpectralFrame(**node)

    @classmethod
    def to_tree(cls, frame, ctx):
        node = cls._to_tree(frame, ctx)

        if frame.reference_position is not None:
            node['reference_position'] = frame.reference_position.lower()

        return node


class CompositeFrameType(FrameType):
    name = "composite_frame"
    types = [CompositeFrame]

    @classmethod
    def from_tree(cls, node, ctx):
        if len(node) != 2:
            raise ValueError("CompositeFrame has extra properties")

        name = node['name']
        frames = node['frames']

        return CompositeFrame(frames, name)

    @classmethod
    def to_tree(cls, frame, ctx):
        return {
            'name': frame.name,
            'frames': yamlutil.custom_tree_to_tagged_tree(frame.frames, ctx)

def from_tree(cls, node, ctx):
        if len(node) != 2:
            raise ValueError("CompositeFrame has extra properties")

        name = node['name']
        frames = node['frames']

        return CompositeFrame(frames, name)

ph_type = list(range(naxes))
        for frame in frames:
            axes_order.extend(frame.axes_order)
        for frame in frames:
            for ind, axtype, un, n, pht in zip(frame.axes_order, frame.axes_type,
                                               frame.unit, frame.axes_names, frame.axis_physical_types):
                axes_type[ind] = axtype
                axes_names[ind] = n
                unit[ind] = un
                ph_type[ind] = pht
        if len(np.unique(axes_order)) != len(axes_order):
            raise ValueError("Incorrect numbering of axes, "
                             "axes_order should contain unique numbers, "
                             "got {}.".format(axes_order))

        super(CompositeFrame, self).__init__(naxes, axes_type=axes_type,
                                             axes_order=axes_order,
                                             unit=unit, axes_names=axes_names,
                                             name=name)
        self._axis_physical_types = tuple(ph_type)