rename
"ADD (0, ADD (1, EMPTYSET))" -> "{0, 1}"
"ADD (1, ADD (0, EMPTYSET))" -> "{1, 0}"
"ADD (0, EMPTYSET)" -> "{0}"
"ADD (1, EMPTYSET)" -> "{1}" 
"EMPTYSET" -> "{}" 
"INSERT (0, INSERT (1, EMPTYL))" -> "{0, 1}"
"INSERT (1, INSERT (0, EMPTYL))" -> "{1, 0}"
"INSERT (0, EMPTYL)" -> "{0}"
"INSERT (1, EMPTYL)" -> "{1}" 
"EMPTYL" -> "{}"