300 random index expressions: 4,311 nodes if each is counted alone, 2,106 distinct nodes in memory
memory while building them (python objects, measured by tracemalloc): 870 KiB, 423 bytes per distinct node
simplify on all 300: 50 ms, 85,490 nodes per second (nodes counted per expression, before simplifying); 2,735 nodes after
p=p+p repeated 18 times: 19 nodes in the graph; as a tree it would have 524,287
