def test_subterms():
a = TableSymbol('a', '{x: int, y: int, z: int}')
assert list(a.subterms()) == [a]
assert set(a['x'].subterms()) == set([a, a['x']])
assert set(a['x'].map(inc).subterms()) == set([a, a['x'], a['x'].map(inc)])
assert a in set((a['x'] + 1).subterms())
