The invention will now be described, by way of example only, with reference to the enclosed figures of drawing, wherein:
FIGS. 1 and 2 have been already described in the foregoing,
FIG. 3 represents, by way of direct comparison to the representation of FIG. 2, a first possible embodiment of the arrangement described herein, and.
FIG. 4 represents, again by way of direct comparison to the representation of FIG. 2, a second possible embodiment of the arrangement described herein.