shapes 3 a and 3 c.
in step 19, a check is made to determine whether there are any phase-one shapes. if there are no phase-one shapes, a jump is made to step 20. if there are any phase-one shapes, a jump is made back to step 15.
when step 19 is performed for the first time, it will be found that phase-one shapes 3 a and 3 c exist, and so a jump will be made to step 15.
when step 15 is performed for the second time, phase-one shape 3 a will be stretched to become a stretched-phase shape 15 a (having a shape and size as in fig. 6), and 