Integrate attr libraries

mtl/test_params.py

@@ -10,11 +10,7 @@ def test_params1(a, b, c):
     phi = mtl.parse('G[a, b] x')
     assert {x.name for x in phi.params} == {'a', 'b'}
 
-    phi2 = phi.set_params({'a': a, 'b': b})
+    phi2 = phi[{'a': a, 'b': b}]
     assert phi2.params == set()
     assert phi2 == mtl.parse(f'G[{a}, {b}](x)')
-
-
-@given(MetricTemporalLogicStrategy)
-def test_hash_stable(phi):
-    assert hash(phi) == hash(mtl.parse(str(phi)))
+