test(tests/lean/run): add new test

tests/lean/run/constr_tac4.lean

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+import data.nat
+
+open nat
+
+definition lt.trans {a b c : nat} (H₁ : a < b) (H₂ : b < c) : a < c :=
+have aux : a < b → a < c, from
+  lt.rec_on H₂
+    (λ h₁, lt.step h₁)
+    (λ b₁ bb₁ ih h₁, by constructor; exact ih h₁),
+aux H₁
+
+definition succ_lt_succ {a b : nat} (H : a < b) : succ a < succ b :=
+lt.rec_on H
+  (by constructor)
+  (λ b hlt ih, lt.trans ih (by constructor))
+
+definition lt_of_succ_lt {a b : nat} (H : succ a < b) : a < b :=
+lt.rec_on H
+  (by constructor; constructor)
+  (λ b h ih, by constructor; exact ih)