$ 'main' \ /---o# \-0(!x!)--i-{i}--e{~}< / \ | | \--------o1---/ $ 'i' \ /-(!q!)(b)a# \-1(!b!)0(!c!)--{d}(c)q{~}< / \ @--m(!b!)------/ \ \--[0001]----(b)(!c!)a1(c)----@ $ 'd' (dup) \-(!d!)(d)(d)# $ '~' \ | /-t-\ # | / \| \-< | \ /| \-f-/ @